Modular print head assembly for plasma jet printing

ABSTRACT

Described herein are apparatus and methods of printing in the presence of plasma. The apparatus includes a modular print head comprising an inlet module, a plasma module with movable electrode configurations, and a nozzle module. The modular design of the print head allows for printing on and treatment of surfaces in many different applications.

CROSS-REFERENCE

This application is a continuation application of U.S. patentapplication Ser. No. 16/922,587, filed Jul. 7, 2020, which is acontinuation application of U.S. patent application Ser. No. 16/649,868,filed Mar. 23, 2020, which claims priority to PCT Application No.PCT/US2018/053703, filed on Oct. 1, 2018, which claims the benefit ofU.S. Provisional Application No. 62/566,488, filed Oct. 1, 2017 and U.S.Provisional Application No. 62/626,171, filed Feb. 5, 2018, each ofwhich applications is entirely incorporated herein by reference.

STATEMENT AS TO FEDERALLY SPONSORED RESEARCH

This invention was made with government support under US Small BusinessInnovation Research (SBIR) Phase 1 Award No. 1819676, awarded by theNational Science Foundation; and SBIR Phase 1 Award No. 80NSSC18P1990,awarded by the National Aeronautics and Space Administration. Thegovernment may have certain rights in the invention.

BACKGROUND OF THE INVENTION

Photolithography, screen printing, laser induced sintering, plasmaspray, inkjet printing, aerosol printing, laser sintering are allexplored for site selective printing of metals and metal oxides, andorganic electronics. Different deposition tools and methods must beadopted for different materials depending on the nature and type ofsubstrate, material to be deposited and the substrate area. This alsomeans increased processing time and increased number of printing toolsrequired for different materials. Plasma printing can be used to print awide range of materials onto the surface of a substrate. Exemplarymaterials that can be printed include organic materials, polymers,inorganic materials, metals, metal oxides, alloys, ceramics, composites,semiconductors, cements, pharmaceuticals, synthetic drugs. Plasmaprinting can provide good adhesion to underlying substrate. In somecases, plasma printing can be an alternative to spray coating, ink jet,aerosol jet printing, screen printing, dip coating, painting and brushcoating.

SUMMARY OF THE INVENTION

Described herein is an apparatus for printing, comprising: a plasmamodule, wherein the plasma module comprises at least one dielectric tubewith at least two electrodes on the outer side of the at least onedielectric tube, and wherein the at least two electrodes can be movedalong the length of the at least one dielectric tube.

In some embodiments, each of the at least two electrodes comprise adielectric encapsulation.

In some embodiments, the dielectric encapsulation has a thickness thatis greater than the thickness of the at least one dielectric tube.

In some embodiments, the dielectric encapsulation has a thickness thatis at least three times greater than the thickness of the at least onedielectric tube.

In some embodiments, the at least two electrodes have different surfaceareas.

In some embodiments, the dielectric encapsulation comprises a firstdielectric material and the dielectric tube comprises a seconddielectric materiel, and wherein the first dielectric material has adielectric strength that is greater than the dielectric strength of thesecond dielectric material.

In some embodiments, the at least one dielectric tube has a length ofabout 10 mm to about 200 mm.

In some embodiments, the at least one dielectric tube comprises aluminumoxide, polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), ora combination thereof

In some embodiments, the at least one dielectric tube has a diameter ofabout 0.02 cm to about 2 cm.

In some embodiments, the at least two electrodes are connected a highvoltage power supply.

In some embodiments, the at least two electrodes generate a plasmawithin the at least one dielectric tube in the presence of a gas.

In some embodiments, the gas comprises argon, helium or a combinationthereof.

In some embodiments, the apparatus further comprises an inlet module.

In some embodiments, the inlet module can be attached to the plasmamodule, and/or detached from the plasma module.

In some embodiments, the inlet module comprises at least one inlet.

In some embodiments, the at least one inlet allows for input of one ormore materials into the inlet module.

In some embodiments, the inlet module allows for flow of the one or morematerials from the inlet module into the at least one dielectric tube ofthe plasma module.

In some embodiments, the one or more materials are exposed to plasmagenerated in the at least one dielectric tube.

In some embodiments, a property of the one or more materials is changedwhen the one or more materials are exposed to the plasma.

In some embodiments, the property comprises an oxidation state, amorphology, a molecular structure, or a combination thereof.

In some embodiments, the apparatus further comprises a nozzle module.

In some embodiments, the nozzle module can be attached to the plasmamodule, and/or detached from the plasma module.

In some embodiments, one or more materials flow from the plasma moduleinto the nozzle module.

In some embodiments, the nozzle module comprises an inner orifice and anouter orifice.

In some embodiments, the inner orifice of the nozzle module is in fluidcontact with the plasma module.

In some embodiments, the inner orifice has a diameter that is less than,equal to, or greater than the diameter of the outer orifice.

In some embodiments, one or more materials exit the apparatus throughthe outer orifice of the nozzle module onto a substrate.

In some embodiments, the outer orifice is in fluid communication with asubstrate.

In some embodiments, the one or more materials are printed on a surfaceof the substrate.

In some embodiments, the one or more materials form a film on thesurface of the substrate.

In some embodiments, the distance between the at least two electrodesalong the length of the at least one dielectric tube by about 1 mm toabout 180 mm.

Described herein is an apparatus comprising: an inlet module, whereinthe inlet module comprises one or more inlets, and an atomizer; and theplasma module described herein.

In some embodiments, one or more materials enter the inlet modulethrough the one or more inlets.

In some embodiments, the atomizer aerosolizes the one or more materialsthat enter the inlet module through the one or more inlets.

In some embodiments, the one or more materials comprise an opticalmaterial.

In some embodiments, the inlet module is in fluid communication with theplasma module.

In some embodiments, the atomizer operates at a frequency of about 50kHz to about 10 MHz.

In some embodiments, the inlet module can be attached to the plasmamodule and/or can be detached from the plasma module.

Described herein is an apparatus comprising: a fluid delivery assembly;and the plasma module described herein.

In some embodiments, the fluid delivery assembly can be attached to theplasma module and/or can be detached from the plasma module.

In some embodiments, the fluid delivery assembly comprises a cartridge.

In some embodiments, the cartridge comprises an ink reservoir.

In some embodiments, the fluid delivery assembly further comprises anatomizer, one or more fluid inlets, one or more fluid outlets, adielectric spacer, a lip, or a combination thereof.

In some embodiments, the fluid delivery assembly is in fluidcommunication with the plasma module.

In some embodiments, the dielectric spacer connects the fluid deliveryassembly to the plasma module.

In some embodiments, the dielectric spacer of the fluid assembly has alength that is greater than the distance between the at least twoelectrodes in the plasma module.

In some embodiments, the fluid delivery assembly comprises two or morecartridges.

In some embodiments, the apparatus comprises the fluid deliveryassembly, the plasma module, and a nozzle module.

In some embodiments, the nozzle module can be attached to the plasmamodule, and/or detached from the plasma module.

Described herein is a method of printing, comprising: introducing one ormore materials to be printed into the plasma module described herein;exposing the one or more materials to plasma in the plasma module, andprinting the plasma-treated one or more materials on one or moresubstrates.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings or figures (also “FIG.” and “FIGs.” herein), ofwhich:

FIG. 1 is a cross sectional view of an exemplary print head fordirecting and accelerating the materials and gas mixtures introducedinto the print head by generating an arc-less plasma.

FIG. 2 is a cross sectional view of an exemplary inlet manifoldconnected to the primary and secondary dielectric tube.

FIG. 3 is cross sectional view of an exemplary plasma manifoldcontaining electrodes that could be moved along the circumference of theprimary dielectric tube, a dielectric enclosure of the electrode, and anouter shield.

FIG. 4 shows cross sectional views of an exemplary modular portion ofthe print head, called plasma manifold, containing electrodes connectedto high voltage power supply. Five different configurations ofelectrodes are shown.

FIG. 5 shows an exemplary gradient plasma setup wherein the primarydielectric tube carries electrodes 221 a, 221 b, 231 a, 231 b connectedto power supplies which can be independently controlled to creategradient plasma and temperature gradient in the primary dielectric tube.

FIG. 6 shows an exemplary primary dielectric tube and an optionalsecondary dielectric tube 140 inside the primary dielectric tube whoselength can be varied depending on the application.

FIG. 7A is a cross sectional view of an exemplary nozzle module that canbe attached to a primary dielectric tube with an orifice whose innerdiameter can either be same as primary dielectric tube or constantlydecreasing and lower than the inner diameter of the primary dielectrictube.

FIG. 7B is a cross sectional view of an exemplary nozzle module that canbe attached to a primary dielectric tube showing the material to beprinted and the after-glow region of the plasma discharge.

FIG. 7C is a cross sectional view of an exemplary nozzle module with aninlet at the nozzle for introducing a gas that can be used for focusingor for tailoring the material properties in glow discharge region of theplasma.

FIG. 8A shows an exemplary printing process using a sacrificial orificeor mask printed on a substrate with precise geometry of printedmaterial. The plasma glow discharge region containing the material thatis directed out of the nozzle for printed with certain geometry and/orresolution can be precisely printed with a high resolution and/orprecision by using a sacrificial mask whose orifice diameter or openingis smaller than the orifice opening.

The sacrificial orifice or mask as shown in FIG. 8B can be indexed whendeposition builds up or for different shape. When an orifice insacrificial mask is clogged or if deposition builds up or when differentpattern is required the sacrificial orifice or mask can be adjusted orreplaced to get a new unclogged orifice and/or a new pattern dependingon the need.

FIG. 9 provides four examples of different shaped sacrificial orificesor patterned masks.

FIGS. 10A and 10B provide photographs of exemplary modular print headsof different configurations.

FIGS. 11A and 11B provide photographs of exemplary modular print headsof different configurations with the plasma ON.

FIGS. 12A and 12B provide photographs of exemplary modular prints headsin a configuration without a nozzle module an in a configuration that iselectrically grounded.

FIG. 13 is a cross sectional view of an exemplary print head foraerosolizing and patterned printing of optical and plasmonic materials.

FIG. 14A is a cross sectional view of an inlet portion of an exemplaryplasma print head comprising one atomizer for aerosolizedliquid(precursor) delivery and two gas inlets connected to an inletmodule and a dielectric tube in which plasma is generated.

FIG. 14B is a cross sectional view of inlet portion of an exemplaryplasma print head comprising one atomizer for aerosolized liquid(precursor) delivery and two gas inlets connected to an inlet module inwhich the atomizer is enclosed in dielectric inlet module and theenclosure.

FIG. 14C is a cross sectional view of inlet portion of an exemplaryplasma print head comprising two atomizers for aerosolized delivery oftwo different liquids/precursors and one gas inlet connected to an inletmodule in which the atomizer is enclosed in dielectric inlet module andthe enclosure.

FIG. 15 is a cross sectional view of an exemplary nozzle and maskassembly showing the mask attached to a piezo motor present in theenclosure and the mask placed in front to the nozzle facing the orifice.

FIG. 16 is a cross sectional view of an exemplary dielectric tube,enclosure and mask assembly showing the mask attached to a piezo motorpresent in the enclosure and the mask placed directly at the outlet ofthe dielectric tube.

FIG. 17 is a cross sectional view of an exemplary non-plasma print head(comprising inkjet or aerosol jet or cold spray equipment) connected toa plasma module, a dielectric tube, an enclosure and mask assemblyshowing the mask attached to a piezo motor present in the enclosure andthe mask placed directly at the outlet of the dielectric tube.

FIG. 18 is a three-dimensional view of an exemplary print head withenclosure.

FIG. 19 is a photograph of an exemplary print head with atomizer ornebulizer, an inlet manifold, a dielectric tube with electrodes and highvoltage cable with an enclosure.

FIG. 20 is a photograph of lower (outlet/printing) portion of print headshowing dielectric with electrodes enclosed, and an enclosure withplasma jet.

FIG. 21 is top view of an embodiment of the orifice controller or themask showing patterned printing and ability to adjust orifice size,shape and printing resolution without having to replace the nozzle.

FIG. 22 is q cross sectional view of an exemplary nozzle module withorifice designed for angular printing.

FIG. 23 shows a modular design of an exemplary fluid delivery assemblywith cartridge mounted to the plasma manifold of the plasma jet printhead.

FIG. 24 shows an exemplary fluid delivery assembly comprising acartridge with atomizer, an ink reservoir, liquid inlets, gas inlets lipand spacer.

FIG. 25 shows an exemplary multi-material fluid delivery system with twocartridges mounted in a single fluid delivery assembly.

FIG. 26 shows an exemplary fluid delivery assembly with cartridgemounted vertically on the coupler.

FIG. 27 shows an exemplary modular design of plasma jet print headcomprising a fluid delivery assembly.

FIG. 28 provides an exemplary fluid delivery assembly.

FIG. 29 provides an exemplary multi-material fluid delivery system withtwo cartridges.

FIG. 30 shows a fluid delivery assembly with a cartridge mountedvertically on a coupler

DETAILED DESCRIPTION OF THE INVENTION

Provided herein is a modular print head assembly for plasma jetprinting, patterning and treatment of surfaces and materials. Patternedprinting, controlled deposition of materials and treatment of materials,using atmospheric pressure plasma, can be used for the manufacturing ofa wide range of products. In some cases, printing of materials with goodadhesion to the underlying substrate and tailored material propertiescan be obtained using atmospheric pressure plasma.

Atmospheric pressure plasma jet printing of wide range of materialsincluding metals, metal oxides, organics, inorganics, organicelectronics, composites, alloys, polymers, drugs, and pharmaceuticals,in a defined pattern and large area can be carried out using any or allof the atmospheric plasma techniques like cold plasma, high temperatureplasma, glow discharge plasma, and plasma spray.

The ability to print a wide range of materials and to mix materials toform polymers, composites, drugs, and alloys for printing, make plasmajet printing a versatile technique in comparison to state of the art andconventional printing, coating, and/or painting techniques.

There are several benefits to plasma in printing including propellingmaterials towards the substrate for printing; changing and/or tailoringmaterial characteristics on-flight to the substrate before, duringand/or after printing; retaining pristine material characteristics;increasing adhesion of the material to the substrate surface;polymerizing plasma; depositing materials in multi-layer; and formationof composites and alloys, to name a few.

Printing of materials and treatment of materials to change theirproperties using atmospheric pressure plasma jet requires optimizedconfiguration of electrodes, electrode spacing and design.

In order to efficiently use plasma jet printing for reliable andreproducible fabrication of devices, high volume production andmanufacturing, and other treatment of materials, the plasma jet printhead should be robust, easy to use, easy to change configuration andeasy to replace.

The print head should have provision to deal with multiple materials,multiple line widths, varying resolution, geometries and small/largearea printing.

In addition, the ability to replace the nozzle in an easy, userfriendly, time effective manner is crucial for long term continued useof the system.

The ability to change the nozzle diameter to effectively change printresolution in an easy, user friendly, time effective manner is alsoimportant for both research and development work as well as for volumemanufacturing.

The characteristics and properties of the materials printed and/ortreated by plasma can be tailored and changed by appropriate choices ofplasma characteristics.

The characteristics of the plasma can be varied by effectively changingthe electrode configuration, electrode surface area, dielectric tube,plasma volume, dielectric area contained between the electrodes, powercharacteristics, or a combination thereof

The plasma jet print head should have the provision to change theelectrode configuration. In addition, the plasma jet print head shouldhave the provision to change the area between the electrodes to tailorthe plasma characteristics to suit certain material printing.

One of the key challenges in plasma jet printing is arcing betweenelectrodes and arcing between the print head and substrate and/orsubstrate holder, if it happens to include metal or metallic printedfeatures. Arcing between electrodes can result in severe damage to theprint head and cause electrical and fire safety issues. Arcing betweenthe print head and the metal substrate or metal substrate holder ormetallic printed features can seriously damage the substrate to beprinted and also the printed features.

For efficient, reliable and reproducible printing of materials usingplasma jet and for volume production of devices using plasma jetprinter, the print head needs to have provisions that allow for flexibleelectrode configuration with modular design; allow for flexible modulardesign of dielectric tubes; avoid failure like arcing between electrodesthat will not only damage the print head but also the substrate; andminimize loss of materials during printing, with minimal or no lossduring movement from the cartridge/reservoir to the nozzle.

Treatment of materials to change chemical structure, molecularstructure, oxidation state, morphology; to inactivate microbes; toremove organics; to decontaminate, or a combination thereof, requiresoptimal configuration of the plasma with provisions for changing theelectrode spacing, thermal gradient, plasma gradient or a combinationthereof, so that the energetic bombardment of plasma-generated speciesand the reactive species generated in plasma can have maximum impact onthe surface being treated.

The electrodes in the print head could be placed in any of a variety ofconfigurations. In some cases, the electrodes are disposed along thecircumference of the dielectric tube. In some cases, the electrodes arearranged with a central tube electrode that is placed inside thedielectric tube and another electrode disposed at the outer wall of thedielectric tube.

Arcing between electrodes can take place either at the inner side of thedielectric tube (internal arcing) or at the outer side of the dielectrictube (external acting) of the print head that can potentially damage theprint head, substrate, or power supply. In addition, this poses aserious electrical safety issues in operation of plasma jet printing.Addressing these safety concerns require appropriate shielding andspacing of electrodes, flexibility in having multiple electrodes withrequired electrode spacing and configuration.

Loss of materials to the inner walls of the dielectric tube duringtransportation and printing is a common issue that needs to beaddressed. Using the primary gas that is used for generating plasmadischarge as the only source of gas for both carrier as well as printingpurpose, this can cause the plasma to extend far beyond the electroderegion and all the way through both the sides of the print head anddielectric tube depending on the applied voltage.

Having an extended plasma throughout the dielectric tube and print headcan be detrimental and can cause loss of materials to the inner walls ofthe tube through collisions. This may result in reduced throughput ofprinting, poor printing performance, loss of dielectric characteristicsof the inner portion of the tube. In some cases, this may further resultin device failure, and need for a larger quantity of precursor materialsfor plasma printing compared to non-plasma printing for same featuresize printing.

One aspect of the disclosure provided herein is a modular print head. Insome embodiments, the modular print head can focus and direct a materialin a geometrical pattern using plasma jet and electric field to printthe material on a substrate. In some cases, the modular print headcomprises a modular assembly of tubes, and movable electrodes. In someembodiments, an electric field is applied to the movable electrodes togenerate plasma. The design of the modular print head avoids internaland external arcing in the tube.

In the following description provided herein, for purposes ofexplanation, specific details are set forth in order to provide anunderstanding of the invention. It will be apparent, however, to oneskilled in the art that the invention can be practiced without thesedetails. Furthermore, one skilled in the art will recognize thatembodiments of the present invention, described below, may beimplemented in a variety of ways, such as a process, an apparatus, asystem, a device, or a method on a tangible computer-readable medium.

References will be made to embodiments of the invention, examples ofwhich may be illustrated in the accompanying figures. These figures areintended to be illustrative, not limiting. Although the invention isgenerally described in the context of these embodiments, it should beunderstood that it is not intended to limit the scope of the inventionto these particular embodiments.

It should be noted that steps or operations may be performed indifferent orders or concurrently, as will be apparent to one of skill inthe art. And, in some instances, well known process operations have notbeen described in detail to avoid unnecessarily obscuring the presentinvention.

Components shown in diagrams are illustrative of exemplary embodimentsof the invention and are meant to avoid obscuring the invention. Itshould also be understood that throughout this discussion thatcomponents may be described as separate functional units, which maycomprise sub-units, but those skilled in the art will recognize thatvarious components, or portions thereof, may be divided into separatecomponents or may be integrated together including integrated within asingle system or component. It should be noted that functions oroperations discussed herein may be implemented as components.Embodiments of the present invention include apparatus and methods forprinting materials with required pattern, material properties andprecision and also treatment of materials, surfaces, organics, microbesfor changing any one or more of the properties including morphology,topography, surface energy, oxidation state, molecular structure,chemical structure etc.

FIG. 1 provides a cross-section view of an exemplary print head 1. Insome embodiments, the print head 1 comprises an inlet manifold 100. Insome embodiments, the print head 1 comprised a plasma manifold 200. Insome embodiments, the print head 1 comprises a nozzle manifold 300. Insome embodiments, the print head 1 comprises a modular assemblycomprising an inlet manifold 100, a plasma manifold 200, a nozzlemanifold 300, or a combination thereof. A modular assembly can allow thedifferent manifolds to be dismantled and connected together as needed,depending on the required plasma characteristic and the type/quality ofmaterials being printed.

In some embodiments, the inlet manifold 100 comprises a dielectricmaterial to create a dielectric inlet manifold 110. In some cases, thedielectric material comprises ceramics. In some cases, the dielectricmaterial comprises aluminum oxide, polyether ether ketone (PEEK),polytetrafluoroethylene (PTFE).

In some embodiments, the dielectric inlet manifold 110 comprises one ormore inlets. The one or more inlets provide for the entry of one or morematerials. In some cases, the one or more materials comprise a gas. Insome cases, the gas comprises helium, argon, hydrogen, nitrogen, or acombination thereof. In some cases, the one or more materials comprise ametallic colloid. In some cases, the metallic colloid comprises a coppernanomaterial, a silver nanomaterial, a gold nanomaterial, or acombination thereof. In some cases, the one or more materials comprise aprecursor material. In some cases, the precursor material comprises anorganic precursor. In some cases, the organic precursor compriseshexamethyldisiloxane, tetraethyl orthosilicate, (3-aminopropyl)triethoxy silane, or a combination thereof. In some cases, thedielectric inlet manifold 110 comprises three inlets 120, 121, and 121.

In some embodiments, the inlet manifold 100 is connected to the plasmamanifold 200. In some cases, the dielectric inlet manifold comprises anopening 130. The opening 130 may allow a primary dielectric tube 210 ofthe plasma manifold 200 to connect with the inlet manifold 100. In othercases, one of the inlets 120 can connect with an optional secondarydielectric tube 140. In those cases, the dielectric tube 140 can have avariable length. The length of the dielectric tube 140 can depend on thenature and the type of material to be printed. In some cases, thesecondary dielectric tube 140 ends before the beginning of the one ormore electrodes 221of the plasma manifold 200. In some cases, thesecondary dielectric tube 140 extends beyond electrode 221 and endsbefore the beginning of electrode 231. In some cases, the secondarydielectric tube 140 extends beyond electrode 231. In some cases, thesecondary dielectric tube 140 extends to the nozzle manifold 300.

FIG. 2 is a cross sectional view of the exemplary inlet manifold 100. Inthis exemplary embodiment, the dielectric inlet manifold 110 comprisesthree inlets 120, 121, and 122. FIG. 2 also provides an optionalsecondary dielectric tube 140.

FIG. 3 is a cross sectional view of an exemplary plasma manifold 220. Insome embodiments, the plasma manifold 220 comprises one or moreelectrodes. In the exemplary embodiment of FIG. 3, the plasma manifold220 comprises two or more electrodes 221, 231 that could be moved alonga circumference of a primary dielectric tube 210. In some embodiments,the electrodes 221 and 231 can contain one or more dielectric enclosures222 and 232 and an outer shield 223 that connect all the three majorportions of the modular print head 1, namely inlet module 100, plasmamodule 200 and nozzle module 300. In FIG. 3, the plasma module 200 cancontain an electrical feedthrough 224 that is connected to the electrode221 with dielectric encapsulation 222. The electrodes 221 and 231 in theplasma manifold are fixed to the primary dielectric tube 210 using anadjustable mechanical position controller 225 and 235. The positioncontroller can be a screw, slide or be made of any adjustable fixture,and can be moved along the axis of the primary dielectric tube 210 bymanual or by using a mini motor. The spacing between electrodes 221 and231 (shown in FIG. 1) can be controlled using the position controller225 and 235 depending on the nature and type of materials being printedand the plasma characteristics required to obtain molecular precision inprinting.

FIG. 4 provides exemplary cross sectional views of a plasma module 200,comprising one or more electrodes. The one or more electrodes can beconnected to high voltage power supply. Different configurations ofelectrodes are shown in FIG. 4 with varying electrode spacing andsurface area. FIG. 4A shows bottom electrode 231 connected to ground andelectrode 221 connected to high voltage. In this embodiment, thesecondary dielectric ends before the top electrode. FIG. 4B shows anadditional electrode 141 dispersed along the circumference of thesecondary inner dielectric 140. FIG. 4C shows the electrode 371 placedoutside the print head, connected to ground while the two electrodes 221and 141 are connected to high voltage. FIG. 4D shows that the bottomelectrode 231 is connected to ground and top electrode 221 is connectedto high voltage while the length of the secondary dielectric 140 isextended till the bottom electrode 231. FIG. 4E shows a ring electrode221 connected to high voltage power supply.

FIG. 5 provides an exemplary gradient plasma setup with an illustrativeprimary dielectric tube 210 comprising one or more electrodes 221 a, 221b, 231 a, and 231 b. The one or more electrodes can be connected topower supplies which can be independently controlled to create agradient plasma and a temperature gradient in the primary dielectrictube.

FIG. 6 provides cross sectional view of an exemplary modular print headcomprising an inlet module and a plasma module. The print head cancomprise a primary dielectric tube 210 and an optional secondarydielectric tube 140. The length of the optional secondary dielectrictube 140 whose length can be varied depending on the application so thatthe material coming out of secondary dielectric tube is either exposedto the entire plasma region comprising two or more electrodes or to apartial plasma region or to a glow discharge region of the plasma closeto the nozzle

FIG. 7A is a cross sectional view of an exemplary nozzle module 300. Insome embodiments, the nozzle module 300 can be attached to the primarydielectric tube 210 of the plasma module 200. In some embodiments, thenozzle module 300 comprises a nozzle with an orifice 330. In some cases,the inner diameter of the orifice 310 can be controlled and varied asneeded depending on the application and type/nature of material beingprinted. In some cases, the diameter of the orifice 330 of the nozzle isthe same at the inner diameter of the orifice 310. In other cases, thediameter of the orifice 330 is smaller than the inner diameter of theorifice 310.

In some embodiments, the nozzle module 300 comprises of a dielectricmaterial 322. In some cases, the dielectric material 322 is surroundedby an outer shield 323. In some cases, the outer shield 323 can beconnected electrically to ground. In some cases, a protective enclosureor housing 324 can be used to connect the nozzle module to the plasmamodule 200 to complete a modular dielectric print head assembly.

FIG. 7B provides an exemplary illustration of a discharge 351 from theorifice 330 of the nozzle module.

FIG. 7C provides an exemplary embodiment of a nozzle module comprising agas inlet 360. In some cases, a gas 361 provided through the gas inlet360 can be used to focus any material exiting the plasma module. In somecases, the gas 361 provided through the gas inlet 360 can tailor one ormore properties of the material in the discharge 351 at the glowdischarge region.

FIG. 8A is an exemplary schematic of printing using the nozzle module ofthe modular print head. The exemplary embodiment comprises printingusing a sacrificial orifice or mask 350, to print on a substrate 353with precise geometry of printed material 352. The plasma glow dischargeregion containing the material 351 is directed out of the nozzle module300 for printing with a geometry of interest, a resolution of interest,or a combination thereof. Printing with a high resolution, a highprecision, or a combination thereof, can be achieved by using asacrificial mask 350. In some embodiments, the diameter of the orificeor opening of the sacrificial mask 350 is smaller than the orificeopening 330 of the nozzle module 300. In some embodiments, the diameterof the orifice or opening of the sacrificial mask 350 is about the sameas the orifice opening 330 of the nozzle module 300. In someembodiments, the diameter of the orifice or opening of the sacrificialmask 350 is greater than the orifice opening 330 of the nozzle module300.

In some embodiments, the sacrificial orifice or mask 350 a as shown inFIG. 8B can be indexed when deposition builds up. In some embodiment,the sacrificial orifice or mask 350 a can be indexed for differentshape.

In some cases, the quality of printing may be disrupted. For example, anorifice in sacrificial mask may become clogged; or deposition may buildup on the sacrificial mask. In those cases, the sacrificial orifice ormask 350 can be adjusted or replaced to get a new unclogged orifice.

In some cases, two or more different patterns may be required forprinting. In those cases, the sacrificial orifice or mask 350 can beadjusted or replaced to get a new pattern depending on the need.

In some embodiments, the sacrificial orifice or mask 350 comprises oneor more orifices or patterns. FIG. 9 shows examples of different shapedsacrificial orifices or patterned masks 350 a, 350 b, 350 c, and 350 d.The patterned masks and the sacrificial orifices could be made of anymaterial including metals, dielectric materials, silicon, plastic, or acombination. The patterned masks and sacrificial orifices could be madeusing any of the known methods including laser etching, wet etching,plasma etching, lithography process, or a combination thereof.

FIG. 10A is a photograph of an exemplary modular print head comprisingan inlet manifold, a plasma manifold and a nozzle manifold. In thisexemplary embodiment, the print head comprises an electrode, adielectric encapsulation of the electrode, a primary dielectric tube,and an electric feedthrough to the electrode. FIG. 10B is a photographof an exemplary modular print of a different configuration. In thisembodiment, the print head comprises ashort electrode spacing.

FIG. 11A and FIG. 11B provide photographs of an exemplary modular printhead with the plasma ON.

FIG. 12A is a photograph of an exemplary print head without the nozzlemanifold with plasma ON. FIG. 12B is a photograph of an exemplary printhead with an electrically grounded shield that can be touched safelyduring the operation of the plasma jet printer.

The primary dielectric tube 210 could be made of any dielectric materialnot limited to ceramic, inorganic materials, including alumina, quartz,teflon, silica, aluminum oxide, or a combination thereof.

The dielectric enclosure 222 and encapsulation shield 232 used toenclose the electrodes 221 and 231 could be made of any insulatingmaterials, ceramics, inorganic materials or mixtures not limited toteflon, macor, alumina, or a combination thereof. Arcing in plasma is acommon phenomenon. Total dielectric strength of encapsulated dielectricis higher than that of the dielectric tube on which electrodes areplaced.

The electrodes and electrical feed throughs could be made of any metal,alloy that conducts electricity including but not limited to copper andstainless steel.

Printing of materials using plasma jet require the precursor or actualmaterial to be printed be introduced in to the plasma jet print headcomprising dielectric tube, electrodes connected to high voltage powersupply, gas supply and a nozzle through which the introduced material isdirected towards the substrate on to which the material is to beprinted.

The precursor or actual material to be introduced into the plasma jetprint head can be in the form of dry particles or aerosolized particlesor aerosolized solution that enters the region where active plasma issustained for sufficient chemical or physical or electronic or molecularor morphological change and are directed to be printed on the substrate.The precursor or actual material may also be introduced into the plasmajet print head in the form of controlled size droplets or controlledvolume liquid or paste dispense.

The precursor or actual material to be printed can also be introduced inthe glow discharge region of the plasma by avoiding interaction of thematerial with active plasma region and hence retaining the pristinematerial characteristics. For this purpose, the material to be printedcan be introduced through secondary dielectric tube.

Plasma jet printing of materials with tailored material characteristicsand defined geometry on a wide range of 2D, 3D objects and soft, or hardsubstrates and for manufacturing in a reliable, reproducible and highthroughput fashion requires a print head that can sustain a stableplasma with several key features including ability to control the plasmacharacteristics through which printed material characteristics can betailored; with the ability to print materials with user definedresolutions, ability to avoid plasma arc between the print headcomponents, electrodes, substrate, substrate holder, printed materialetc., ability to sustain temperature gradient in print head for printingmaterials with varying temperature allowing the operating temperature ofthe substrate to vary from 20° C. to several hundred degree Celsius.

In one configuration, the ability to print materials with printedgeometries between 50 nm and 500 um with control over the repeatabilityand accuracy of the resultant geometry is provided. In anotherconfiguration, the ability to print materials with printed geometries ofbetween 500 um and 10 cm is provided. In another configuration, theability to print materials with printed geometries of between 10 cm and50 cm is provided. Similarly, the ability to treat materials andsubstrates with plasma for all the above defined geometry ranges isprovided. Some configuration allows use of multiple print headssimultaneously to print and treat materials on a large area.

The ability to print a variety of materials with controlled but variablemorphologies including amorphous, agglomerated particle, porouscontinuous or non-continuous is provided.

The ability to precisely control the printed material rate of depositionand thickness of deposition during printing by means of manipulating theplasma characteristics and/or the delivery of the material being printedis provided.

Printing materials using plasma jet with defined geometry and tailoredmaterial characteristics including physical, chemical, mechanical,electronic, optical, bio-interface, biocompatible properties requireoptimum plasma characteristics to obtain any one or more combination ofabove mentioned material properties. For example, nature and type ofplasma gas, plasma density, electron temperature, ion temperature, freeradical generation, available volume between electrodes, electrodeconfiguration, number of active electrodes etc., can play a significantrole in printing materials with any of the required properties includingphysical, chemical, mechanical, electronic, magnetic, optical,bio-interface, biocompatible properties etc.,

A plasma jet printer is disclosed, that can print wide range ofmaterials on wide range of substrates including 2D, 3D, hard, soft,continuous, porous, flexible, rigid, vials, wells etc., can be used inmanufacturing in various fields including electronics, textiles,medical, wearable, automobile, aerospace, energy storage/generation,display, food packaging, sensors, implants, test equipment etc.,

Printing a wide range of materials with unique material characteristicfor any or all field of use application requires appropriate precursormaterials, appropriate substrate, appropriate processing environmentlike humidity, temperature, pre-treatment of substrate, masks, printing,post-treatment, curing etc.

However, plasma jet printing of wide range of materials with tailoredmaterial characteristics requires a key component, namely a controlledplasma environment that can change, modify or control the properties ofthe material that goes through the plasma region or retain thoseproperties depending on the need. Say for example, printing ofconducting materials will require prevention of oxidation, reduction ofmaterials in-situ or post printing, partial or full melting ofmaterials, etc., For printing of organic coatings, polymerization isessential. For printing of organic electronics or chemicals or drugs,retaining of chemical structure is essential. For printing of dielectriccoatings with varying dielectric strength, the chemical compositionneeds to be varied. For printing biocompatible coatings, retaining thechemical structure of drugs is essential.

For printing of organics, inorganics, metals, metal oxides,semiconductors, magnetic materials, ceramics, polymers, drugs,chemicals, small organic molecules, big organic molecules, or acombination, the plasma characteristics in the print head and the gascomposition, precursor composition will have to be precisely controlled.Though the precursor composition and gas composition can easily becontrolled with appropriate use of ink cartridge and gas supply line,controlling the plasma characteristics for printing require optimalconfiguration of several key components including dielectric strength ofthe dielectric print head and the tube thickness, electrodeconfiguration, electrode spacing, dielectric encapsulation ofelectrodes, volume of the portion of dielectric tube that contains theactive plasma region, number of live/ground/floating electrodes, natureand type of nozzle, orifice diameter in nozzle, particle feeding rateetc.,

Modular design of the print head with multiple feed throughs forprecursor and gas inlet, multiple dielectric tubes connected through amanifold and placed inside the main dielectric tube containingelectrodes in which the plasma is generated, adjustable electrodespacing, replaceable nozzles with varying orifice diameter for printing,provision to increase or decrease the total number of electrodes in theprint head, dielectric encapsulation of electrodes, uneven electrodeareas can all play a significant role in deciding the optimum parametersneeded for printing specific class of materials, the quality of theprinted material as well as the nature of material that can be printed.

For example, a modular design of the print head that is optimized forprinting 10 microns thick uniform conducting metallic features withdefined line resolution (say 50 microns) from the corresponding metaloxide input, will allow increased dwelling time of metallic particles inthe plasma containing reducing gas environment and also highertemperature in specific regions of the dielectric tube. The number ofelectrodes, electrode spacing, plasma volume, particle/aerosol/precursorfeeding, nature and type of nozzle, orifice diameter, applied potentialwill have to be optimized to obtain a plasma characteristic that willmake maximum use of plasma parameters/properties to reduce metal oxideto metal and also to partially or fully melt metallic input to form acontinuous metal film with precise 50 microns conducting metallic linefeature.

However, a modular design of the print head for printing a 10 nanometerthick organic polyethylene glycol coating with a line width of 5millimeters on a biosensor or medical device will have the electrodedesign in such a way that the plasma characteristics are not too intenseto damage the chemical structure of the precursor or the substrate andat the same time enabling plasma polymerization to take place. Thenumber of electrodes, electrode spacing, plasma volume,particle/aerosol/precursor feeding, nature and type of nozzle, orificediameter, applied potential will be optimized for this application andthe parameters will be different than that of printing metal from metaloxides with fine feature.

The idea behind the modular design of the plasma jet print head is toallow optimization of the print head design, configuration and processparameters for specific application.

Also the modular design of the plasma jet print head enables integrationof the print head to other printing techniques like aerosol jetprinting, spray pyrolysis, ink jet printing, laser printing, dropcasting etc.,

Use of high voltage power supply is essential for generating plasmadischarge. The high voltage is applied between the electrodes in thedielectric tube of plasma jet print head. The nature and type of powerinput can vary from DC, pulsed DC, AC to RF. The power supply can eitherbe battery powered or connected to a high voltage source. Use ofmultiple electrodes in the same print head will allow application ofvarying input energy to selected electrodes resulting in gradient plasmain the dielectric tube.

A modular design with two electrodes in the print head could result inuniform plasma. However, in a modular design with an elongateddielectric tube with four electrodes in the print head, two electrodescould be connected to a power supply with higher input energy and twoother electrodes could be connected to the same or different powersupply with lower input energy than the other electrodes. In this case,the plasma characteristics in higher input region is likely to be have ahigher ion energy, electron/ion temperature, plasma density etc., thanthat of the lower energy input region. This design can be used tointroduce temperature gradient in the print head and for increaseddwelling time of the materials in the plasma. Both the electrode setscould also be connected to similar potential resulting in uniform plasmaacross the entire print head.

Use of high voltage power supply and generation of plasma can alsoresult in arcing between the metallic components of the print head orthe printer assembly. The arcing can happen between the electrodes ofthe print head, the plasma and the substrate or substrate holder, or themetallic coating being printed. The modular design of the plasma jetprint head assembly provides a solution to avoid arcing during theprinting and post-printing.

The modular design of the plasma jet print head comprise a manifoldconnected to the primary dielectric tube on which electrodes connectedto high voltage power supply are dispersed. The manifold will haveprovision for gas input and precursor/material inlet and a provision toconnect dielectric tubes from the gas input and/or precursor/materialinput inside the primary dielectric tube whose length can be controlleddepending on the application. The inner dielectric tubes placed insidethe primary dielectric tube can carry the precursor or gas or both. Themodular design also allows the provision to have a manifold with inletsfor gas and precursor without multiple dielectric tubes and containingonly the primary dielectric tube inside which both the gas andprecursor/material are introduced.

The length and diameter of the primary dielectric tube in the modulardesign can be varied depending on the nature and type of material to beprinted and the application. The thickness, dielectric strength anddiameter of the dielectric tube can vary the plasma characteristics andthe temperature inside the tube allowing for tailoring the materialproperties of the printed features/structures. The modular design allowsjoining of two or more dielectric tubes that are similar or of varyingdiameters along the longitudinal axis.

In some embodiments, the diameter of the dielectric tube is about 0.02cm to about 2 cm. In some embodiments, the diameter of the dielectrictube is at least about 0.02 cm. In some embodiments, the diameter of thedielectric tube is at most about 2 cm. In some embodiments, the diameterof the dielectric tube is about 0.02 cm to about 0.05 cm, about 0.02 cmto about 0.1 cm, about 0.02 cm to about 0.5 cm, about 0.02 cm to about 1cm, about 0.02 cm to about 1.5 cm, about 0.02 cm to about 2 cm, about0.05 cm to about 0.1 cm, about 0.05 cm to about 0.5 cm, about 0.05 cm toabout 1 cm, about 0.05 cm to about 1.5 cm, about 0.05 cm to about 2 cm,about 0.1 cm to about 0.5 cm, about 0.1 cm to about 1 cm, about 0.1 cmto about 1.5 cm, about 0.1 cm to about 2 cm, about 0.5 cm to about 1 cm,about 0.5 cm to about 1.5 cm, about 0.5 cm to about 2 cm, about 1 cm toabout 1.5 cm, about 1 cm to about 2 cm, or about 1.5 cm to about 2 cm.In some embodiments, the diameter of the dielectric tube is about 0.02cm, about 0.05 cm, about 0.1 cm, about 0.5 cm, about 1 cm, about 1.5 cm,or about 2 cm.

The electrodes that will be connected to a voltage source are dispersedalong the primary dielectric tube. The number of electrodes can be twoor more and the surface area of one of the electrodes is more thandouble that of the second electrode. The electrodes can either be placedalong the outer circumference of the dielectric tube, or one of theelectrodes can be placed inside the dielectric tube and the other alongthe outer circumference, or the electrodes can be embedded inside thedielectric tube such that the portion of electrodes are exposed to theinner portion of the dielectric tube.

One or all of the electrodes can either be similar in shape or more thanone can be of any shape like that of a planar tape or wire like windingalong the circumference or pointed edge or sharp blade like whenembedded inside the dielectric or one of the electrodes can be rodshaped and placed inside the dielectric. However, in all these casesexcept for electrodes that are embedded inside the dielectric, theelectrode separation distance can be changed depending on the requiredconfiguration/application/quality of printing and the electrodesdispersed along the circumference of the dielectric are movable alongthe longitudinal axis.

In some embodiments, the distance between the first electrode and thesecond electrode is about 5 mm to about 40 mm. In some embodiments, thedistance between the first electrode and the second electrode is atleast about 5 mm. In some embodiments, the distance between the firstelectrode and the second electrode is at most about 40 mm. In someembodiments, the distance between the first electrode and the secondelectrode is about 5 mm to about 10 mm, about 5 mm to about 15 mm, about5 mm to about 20 mm, about 5 mm to about 25 mm, about 5 mm to about 30mm, about 5 mm to about 35 mm, about 5 mm to about 40 mm, about 10 mm toabout 15 mm, about 10 mm to about 20 mm, about 10 mm to about 25 mm,about 10 mm to about 30 mm, about 10 mm to about 35 mm, about 10 mm toabout 40 mm, about 15 mm to about 20 mm, about 15 mm to about 25 mm,about 15 mm to about 30 mm, about 15 mm to about 35 mm, about 15 mm toabout 40 mm, about 20 mm to about 25 mm, about 20 mm to about 30 mm,about 20 mm to about 35 mm, about 20 mm to about 40 mm, about 25 mm toabout 30 mm, about 25 mm to about 35 mm, about 25 mm to about 40 mm,about 30 mm to about 35 mm, about 30 mm to about 40 mm, or about 35 mmto about 40 mm. In some embodiments, the distance between the firstelectrode and the second electrode is about 5 mm, about 10 mm, about 15mm, about 20 mm, about 25 mm, about 30 mm, about 35 mm, or about 40 mm.

In some embodiments, the distance between the electrodes is about 1 mmto about 180 mm. In some embodiments, the distance between theelectrodes is at least about 1 mm. In some embodiments, the distancebetween the electrodes is at most about 180 mm. In some embodiments, thedistance between the electrodes is about 1 mm to about 10 mm, about 1 mmto about 25 mm, about 1 mm to about 50 mm, about 1 mm to about 75 mm,about 1 mm to about 100 mm, about 1 mm to about 125 mm, about 1 mm toabout 150 mm, about 1 mm to about 180 mm, about 10 mm to about 25 mm,about 10 mm to about 50 mm, about 10 mm to about 75 mm, about 10 mm toabout 100 mm, about 10 mm to about 125 mm, about 10 mm to about 150 mm,about 10 mm to about 180 mm, about 25 mm to about 50 mm, about 25 mm toabout 75 mm, about 25 mm to about 100 mm, about 25 mm to about 125 mm,about 25 mm to about 150 mm, about 25 mm to about 180 mm, about 50 mm toabout 75 mm, about 50 mm to about 100 mm, about 50 mm to about 125 mm,about 50 mm to about 150 mm, about 50 mm to about 180 mm, about 75 mm toabout 100 mm, about 75 mm to about 125 mm, about 75 mm to about 150 mm,about 75 mm to about 180 mm, about 100 mm to about 125 mm, about 100 mmto about 150 mm, about 100 mm to about 180 mm, about 125 mm to about 150mm, about 125 mm to about 180 mm, or about 150 mm to about 180 mm. Insome embodiments, the distance between the electrodes is about 1 mm,about 10 mm, about 25 mm, about 50 mm, about 75 mm, about 100 mm, about125 mm, about 150 mm, or about 180 mm.

The electrodes are part of the modular design of the print head in whichthe number, size and spacing of the electrodes can be easily changedproviding an opportunity to control plasma characteristics throughapplication specific, precise configuration of electrodes for reliableand reproducible printing of materials with tailored characteristics.Generating plasma using multiple electrodes dispersed along thedielectric and applying similar or varying potentials to various sets ofelectrodes can create a gradient in plasma characteristics. In somecases, a temperature gradient is created which will drastically changethe material properties such as increasing dwelling of materials in theplasma zone and resulting in change of electronic or mechanical oroptical or chemical properties of the resultant printed feature.

The provision to change spacing between the electrodes provides theopportunity to change plasma characteristics and hence the quality ofmaterials printed. For example, two electrodes dispersed along the outercircumference of the dielectric tube with 1 centimeter spacing betweenthem will have a certain plasma characteristics for a given externallyapplied electric potential. However, for the same potential, if theelectrode spacing is increased to 2 centimeters the plasmacharacteristics will be different and higher potential will be requiredto ignite and sustain the plasma. The quality of films printed under thetwo configurations could vary significantly for a given set of fixedplasma process parameters like flow rate, applied voltage, printingtime, or a combination thereof.

Changing the spatial distribution of electrodes to print materialsallows changing parameters like thermal energy in the plasma, electronand ion density in the plasma, bombardment between various species inthe plasma and the material to be printed, and also momentum transferredon to the materials and substrate during printing. A plasma jet printhead with safe option to change the electrode spacing in a single stepprocess without having to remove the electrode from the print headoffers a unique capability to tune the properties of the materialsprinted using the plasma jet print head.

The print head described herein can connect multiple electrodes in aconfined zone and without any electrical arc between any of the internalcomponents of the print head or with the substrate or with the substrateholder or with the material being printed. An apparatus for printingmaterials using plasma jet in a defined geometry with a modular printhead design comprising detachable dielectric tubes, metal electrodes anddielectric encapsulations that avoids arcing between electrodes,substrate, substrate holder, coated material for printing materials withtailored material properties is disclosed.

The modular design of the plasma jet print head allows for attachingdielectric tubes along the longitudinal axis that can be used forfocusing the materials towards substrate for printing. The ability toincrease, decrease, narrow or widen the length, diameter and volume ofthe dielectric tube provides an opportunity to change the plasma volumeand in turn tune the interaction of the material to be printed with theplasma.

The modular design of the plasma jet print head allows for attaching orremoving a replaceable nozzle with defined orifice diameter that can beused for printing required feature size and resolution. The orificediameter can either remain the same as the dielectric tube or it can benarrowed to suit the required resolution varying from 5 centimeters to 5microns to further down to submicron level to 50 nm with the use ofsilicon micro-machined nozzle. In another configuration, large areacoating could be achieved by having multiple dielectric tubes or printheads for simultaneous printing or use of larger diameter orificegreater than 5 cm.

The narrow orifice and design of the nozzle along with the externallyapplied electric field and presence of plasma helps driving the materialentering the dielectric tube to get focused and accelerated towards thesubstrate enabling high resolution and high throughput printing.

The modular design of the print head also allows the introduction of aninert or higher dielectric strength gas (than the ones used forgenerating plasma) at the nozzle as a sheath gas for focussing thematerial towards the substrate.

The nozzle that can be easily replaced and also attached to the primarydielectric tube can comprise a plain dielectric material with an orificeor be designed with a continuously narrowing inner dimension to allowfor fine resolution printing or contain a metal inside or at the edgethat can either be at floating potential or connected to ground. Thepresence of metal at the nozzle can play a significant role in reducingarcing between the plasma in the print head and substrate or substrateholder or the material being printed.

Arcs in plasma and high voltage are a common phenomenon. However, forprinting application arcing should be avoided as it can damage thesubstrate or the components of the print head. The modular design of theprint head allows a stable arc-less plasma to sustain and prevent arcingbetween the electrodes or arcing between the plasma and substrate orsubstrate holder or material being printed.

Applying high voltage to electrodes placed along the circumference ofthe dielectric tube can cause arcing either external to the dielectric,here after called as external arcing, or internal to the dielectrictube, here after called as internal arcing, or both. For printingapplications, both internal and external arcing between the electrodesshould be prevented.

The modular design of the print head incorporates multiple features thatprevent arcing between the electrodes or arcing between the plasma andthe electrodes in the print head. One of the ways to prevent arcing isto use uneven surface area of electrodes. Another way is to use thickerdielectric encapsulation of electrodes so that the electrodes are notexposed to ambient environment.

With the electrodes dispersed along the circumference of the dielectrictube, one of the electrodes has a surface area more than double that ofthe other electrode, such that the electric field is spread over alarger area, minimizing arcing.

A key feature to prevent arcing between electrodes that are dispersedalong the outer circumference of the dielectric tube is to encapsulatethe electrodes with dielectric material whose thickness is more thanthrice that of the thickness of the primary dielectric tube on which theelectrodes are dispersed. The total dielectric strength of theencapsulated dielectric is higher than that of the primary dielectrictube on which the electrodes are dispersed.

The carrier gas that carries the aerosolized material to be printed andthe gas that is used to generate plasma discharge can either be same ordifferent depending on the nature of the material and the requiredresultant printed material properties. In the case where the effect ofplasma species on the materials is to be minimized and restricted to aminimal region containing plasma, a non-interactive higher dielectricstrength carrier gas can be used to transfer the material and a gas withlower dielectric strength like that of argon or helium be used togenerate plasma discharge. The higher dielectric strength carrier gascan also be used as a focusing gas at the nozzle and the modular designallows feeding the required gas mixtures either at the input manifold ofthe print head or closer to the electrode in the dielectric tube or atthe nozzle.

The modular design of the print head that allows connecting multipleelectrodes (more than 2) in the dielectric tube, provision to controlthe plasma volume and the interaction time of plasma species with thematerials and provision to introduce required gas mixture in any portionof the dielectric tube like that of inlet manifold, before or in betweenor after the electrodes allows intricate control of the plasmacharacteristics and in turn allows tailoring of the material propertiesresulting in printing of custom made material.

Multiple electrodes powered with varying input energies for generatingplasma with either the same gas mixture or different gas mixtures allowdual plasma zones in the primary dielectric tube as shown in FIG. 5. Theregion inside the dielectric tube has different plasma characteristicsin each plasma zone. For example plasma zone 1 with higher inputelectric energy across the electrodes 221 a and 221 b can have highertemperature and plasma zone 2 with lower input electric energy acrossthe electrodes 231 a and 231 b can have lower temperature. Plasma zone 1inside the primary dielectric tube between the electrodes 221 a and 221b can have reducing environment and plasma zone 2 between the electrodes231 a and 231 b can have inert environment. This allows intricatecontrol of both temperature driven and chemically driven modification ofthe printed material. Plasma zone 2 can act as a focusing or a coolingunit while still maintaining an active plasma region enabling printingon low glass transition materials.

Plasma zone 1 provide optimal conditions for chemical, electronic,magnetic, structural or morphological modification of the material,plasma zone 2 can remain optimized for best printing propertiesdepending on the substrate, temperature, adhesion, pre-treatment,post-treatment etc., requirement.

The print head can generate atmospheric pressure plasma that directs andprints materials onto the substrate where the substrate temperatureduring the printing process can vary from as low as 20° C. to as high as300° C. as determined by the electrode configuration, electrode spacing,applied power, dielectric tube, nature of gas, to name a few. In somecases, the substrate temperature is about 20° C. to about 300° C. Insome cases, the substrate temperature is at least about 20° C. In somecases, the substrate temperature is at most about 300° C. In some cases,the substrate temperature is about 20° C. to about 50° C., about 20° C.to about 75° C., about 20° C. to about 100° C., about 20° C. to about125° C., about 20° C. to about 150° C., about 20° C. to about 175° C.,about 20° C. to about 200° C., about 20° C. to about 225° C., about 20°C. to about 250° C., about 20° C. to about 275° C., about 20° C. toabout 300° C., about 50° C. to about 75° C., about 50° C. to about 100°C., about 50° C. to about 125° C., about 50° C. to about 150° C., about50° C. to about 175° C., about 50° C. to about 200° C., about 50° C. toabout 225° C., about 50° C. to about 250° C., about 50° C. to about 275°C., about 50° C. to about 300° C., about 75° C. to about 100° C., about75° C. to about 125° C., about 75° C. to about 150° C., about 75° C. toabout 175° C., about 75° C. to about 200° C., about 75° C. to about 225°C., about 75° C. to about 250° C., about 75° C. to about 275° C., about75° C. to about 300° C., about 100° C. to about 125° C., about 100° C.to about 150° C., about 100° C. to about 175° C., about 100° C. to about200° C., about 100° C. to about 225° C., about 100° C. to about 250° C.,about 100° C. to about 275° C., about 100° C. to about 300° C., about125° C. to about 150° C., about 125° C. to about 175° C., about 125° C.to about 200° C., about 125° C. to about 225° C., about 125° C. to about250° C., about 125° C. to about 275° C., about 125° C. to about 300° C.,about 150° C. to about 175° C., about 150° C. to about 200° C., about150° C. to about 225° C., about 150° C. to about 250° C., about 150° C.to about 275° C., about 150° C. to about 300° C., about 175° C. to about200° C., about 175° C. to about 225° C., about 175° C. to about 250° C.,about 175° C. to about 275° C., about 175° C. to about 300° C., about200° C. to about 225° C., about 200° C. to about 250° C., about 200° C.to about 275° C., about 200° C. to about 300° C., about 225° C. to about250° C., about 225° C. to about 275° C., about 225° C. to about 300° C.,about 250° C. to about 275° C., about 250° C. to about 300° C., or about275° C. to about 300° C. In some cases, the substrate temperature isabout 20° C., about 50° C., about 75° C., about 100° C., about 125° C.,about 150° C., about 175° C., about 200° C., about 225° C., about 250°C., about 275° C., or about 300° C.

The modular design of the print head has the provision to introduceprecursor, gas or other material to the print head in more than one wayto get tailor-made material properties and or materials with pristineproperties as in the original precursor. This can be achieved by havingplurality of inputs and/or dual dielectric tubes.

The print head input manifold may have one input for the precursor andgas, or one input for both precursor and gas, to enter into the primarydielectric tube. The manifold may also have plurality of inputs for morethan one precursor, or gases, to enter the primary dielectric tube,either one at a time or simultaneously.

The modular design of the print head allows for one or more inputs forthe precursors, or gases, to enter into the primary dielectric tube andthere may be a secondary dielectric tube within the primary dielectrictube. In this configuration, the precursors may enter into either theprimary or secondary dielectric tube, or both, one at a time orsimultaneously. The electrodes in this configuration are present inouter dielectric tube and the length of the inner dielectric tube canvary. The length of the inner secondary dielectric tube can either besame as the outer primary dielectric tube or shorter. The length of theinner secondary dielectric tube can be varied in such a way that thedielectric tube can end well before the electrode placed at the outerprimary dielectric or stretch all the way unto the nozzle or take anyintermediary length independent of the length of the primary dielectrictube.

Depending on the gas constituent and or precursor/material input fromthe primary dielectric and the length of the secondary dielectric placedinside the primary, the precursor/material or gas introduced through thesecondary dielectric can either face the active plasma region created bythe electrodes dispersed over the primary dielectric tube or face onlythe glow discharge region of the place at the nozzle or at the exit ofthe nozzle. This allows the materials introduced through the secondarydielectric tube to either undergo plasma induced property changes ormaintain its pristine characteristics without undergoing plasma inducedstructural, chemical or material property changes.

The modular design of the print head allows for multiple dielectrictubes to be present with provision for including one or more secondarydielectric tubes within the primary dielectric tube. The inputs to theprimary and the secondary dielectric tubes can again be independentlycontrolled and also the length of all or any of the secondary dielectrictube can either be same as primary dielectric tube or shorter than theprimary dielectric tube.

The modular assembly of the print head allows for further improving theresolution by placing a patterned focusing apparatus with a definedorifice whose opening is smaller than the orifice of the nozzle. Themodular design allows for the utilization of a patterned or controlledgeometry sacrificial mask to print though, providing an additional meansfor transferring a precise pattern to the substrate or further refiningthe geometry of the print by restricting the area of the substrateexposed to the print medium. This may be as simple as an additionalorifice that is smaller than the nozzle exit orifice that acts as a wayof reducing the print jet. This additional orifice allows for the nozzleorifice to be larger than normal not the geometry defining orifice andso less susceptible to a buildup of printer material interfering withthe resolution of the resultant print. The printer further provides anautomated means of changing such sacrificial masks or orifices.

The modular design of the print head not only allows replacement ofnozzle but also allows replacement of nozzle tip which is placed at theend of the nozzle for fine resolution or patterned printing. Using apatterned nozzle tip at the end of the nozzle allows fine resolutionprinting with a fixed nozzle whose orifice diameter is bigger than thatrequired for printing and bigger than the orifice of this patterned tipwhich is replaceable. The modular design also allows for the ability toextend the lifetime of the nozzle before it needs cleaning orreplacement due to buildup of deposited material on the inner diameterof the nozzle orifice which would change the geometry of the print.Further, such a replaceable nozzle tip allows for variable geometryprint control with a single nozzle.

The modular design of the print head allows for configuration ofmultiple nozzles in one printer for multi-material printing. The abilityto configure with multiple nozzles in one printer system or to configurewith nozzles in a cluster arrangement allows for multiple materials tobe printed on a substrate within the same system either one afteranother or simultaneously or, in a cluster configuration, for multiplematerials to be printed on a substrate in separate chambers one afteranother where each chamber performs a different step of the overallprocess thus facilitating parallel steps within the same printer.

The precursor input to print head may occur through a nebulizer thatcreates an aerosol of materials to be printed. The nebulizer can beindependently controlled by having features to control droplet size ofaerosolized material: allowing for atomized droplet size to be varied asanother means of optimizing the characteristics of the printed materials

Printing of electronic circuits, conductive traces, passive electroniccomponents is normally carried out on planar substrates. The need forprinting conductive traces and circuits on polymers, non-planarsurfaces, 3D objects and on steps, vials, wells etc., is everincreasing, especially in interconnect technologies, fan out wafer levelpackaging, laboratory devices, testing using well plates etc.Traditionally used deposition technologies like magnetron sputtering,electro chemical coating, thermal evaporation etc., are no longerappealing for these applications. Direct write printing techniques likescreen printing, ink jet printing and aerosol jet printing are beingwidely researched as an alternative route for printing. Printing onvials, steps, wells etc., whose aspect ratio is high and the depthvaries from few tens of micrometers to few millimeters is challenging.There is a need to get highly directional printing that can print insuch long working distance. The modular design of the plasma jetprinting offers the ability to control the fluid flow and the jet usingplasma process parameters and the applied voltage and hence has thepotential to print in vials, steps, wells, 3D objects etc.,

Printing of electronic materials including conducting and insulatinglayers on vials, steps, wells and non-planar surfaces requirestechniques that enable printing over a long working range. The workingdistance between the print head nozzle and the substrate on whichprinting to be carried out is normally very small, in the range of fewmillimeter in state of the art printers like inkjet and aerosol jetprinting. For applications that involve printing on vials, steps, wellsthat are three dimensional, the need is efficient and directed deliveryof particles on to these surfaces. The plasma jet controlled byexternally applied electromagnetic field can be efficiently used toprint materials on vials, wells, steps and non-planar surfaces. Theprint head nozzle containing decreasing throat diameters can be usedsuccessfully to print fine traces and patterns on such three dimensionalsurfaces.

There is a growing need for advanced metallization techniques for 3Dinterconnects in through silicon via (TSV) and 3D integration inintegrated circuit (IC) packaging. There is also a demand for printingconductive patterns including printed circuit boards, interconnects,antenna, bumps in a range of substrates with varying glass transitiontemperature and outgassing properties.

Flexible electronics, displays and wearable monitoring technologiesrequire printing of conducting materials including conducting organicsand/or metal coatings and interconnects on flexible and non-traditionalsubstrates like plastics, cellulose, polymers, textiles where theconventional techniques for metallization are difficult to apply. Themodular design of the plasma jet print head allows for printing of theseconducting and insulating materials and electronic devices on these widerange of substrates.

The modular design of the print head allows for printing of electrodesfor devices including batteries, fuel cells, photovoltaic devices,photocatalytic converters etc., The electrodes can be planar and/orporous, with appropriate morphology for efficient energy conversion,energy generation, storage etc.,

The modular design of the plasma jet print head allows for printingbatteries, flexible batteries, battery electrodes, porous electrodes,flexible electrodes, and also enable battery fabrication usingbinder-free methods. Plasma jet printing using a modular design allowscomplete removal of inactive binder in the electrodes or for theinactive binder components in electrodes to be kept to a lower levelcompared to other printing techniques.

Porous metallic nanostructure films printed using the modular print headdesign can be used as electrodes for batteries accounting for expansionand contraction with temperature and duty cycle. The porous metallic ormetal-oxide structure with nano roughness that is critical for catalystand CO₂ conversion can also be printed using the modular design of theprint head. Also metal composites such as TiO₂ nanostructure filmcontaining copper (Cu—TiO₂ co catalyst) can also be printed using themodular design for CO₂ conversion.

Nanostructures of various metal, metal oxide, transition metals andcomposites can be printed with required oxidation state, composition andmorphology using the modular design of the print head. The plasmaprocess parameters and the modular design can be optimized to printco-catalyst composites to get high CO₂ conversion efficiency and highcatalyst reliability. For example Cu—TiO₂ co-catalyst, iron-copper oxide(Fe—CuO) co-catalyst, Cu-based nanoparticles (copper oxides, and hybridcopper nanostructures) and copper nanoparticles immobilized into orsupported on various support materials.

The modular design of the plasma jet print head can be used to fabricateand embed catalysts for effective conversion of CO2 to oxygen andhydrocarbons in a range of applications including emission gas reductionin automobile industry, power plants, space station etc., The plasmaproperties and process parameters like the applied voltage, gas ratio,precursor flow ratio, electrode design can be used to fabricate theco-catalyst and print with appropriate composition and morphology to getmaximum possible conversion efficiency by enabling artificialphotosynthesis. The printing can be done on a range of substratesincluding waveguides, planar, non-planar surfaces.

The modular design of the print head can be used for a range ofapplications including printing and coating of polymers, organics,inorganics, graphene, graphene oxide, reduced graphene oxide, metals,alloys, composites, semiconductors, magnetics, insulators etc., Thisprovides a method to print polymers in a dry form on a range ofsubstrates for applications including wearables, wearable monitors,textiles, cloths, shoes, medical devices, implants, diagnostic devices,etc., and avoid thermal curing, annealing or post treatment process toincrease polymerization or to remove materials (impurities, solvents).

The modular design of the plasma jet print head can be used to makemetal-polymer composites, alloys, polymeric coatings, layered coatings,porous coatings, hybrid inorganic/organic materials, metal-organichybrid etc., for a wide variety of applications. The plasma processparameters and the modular design of the print head allows printing avariety of material compositions, structures and morphologies in a dryform as thin, thick, or porous films, with or without patterning in adry form.

The plasma jet print head can be used to print plasmonic nanostructures,plasmonic film, plastic-metal layered plasmonic features to fabricatenanostructured plasmonic devices for a range of applications includingbiosensing, photonics communication, optical devices etc., The plasmaprocess parameters, print head design and printing time can be used tocontrol the density of packing of plasmonic nanostructures like gold,silver etc., and also the layer thickness.

The plasma jet printing can be used to print organics includingcellulose, polymers etc., and also composites to create organic films ofdifferent densities, cross-linked strengths and rigidities.

The modular assembly of the plasma jet print head allows printing ofcarbonaceous materials including carbon nanotubes, graphene oxide etc.,and also allows both in-situ and post printing reduction and oxidationof these nanomaterials.

The modular assembly of the plasma jet print head allows the treatmentof materials on a surface by using appropriate gas mixtures andtemperature gradient in active plasma regions if necessary where by themorphology, surface chemistry, and/or surface energy of the materials onthe surface can by changed. For example, by treatment of a planar coppersurface with argon or helium or hydrogen or a gas mixture plasma, coppernanomaterial features can be formed on the surface. A planar coppersurface may be turned into copper nanowires by morphological andtopographical changes. Copper oxide reducing to copper by change ofoxidation state of copper by reduction may be achieved.

The modular assembly of the plasma jet print head can also allow for thetreatment of organics and microbes on the surface whereby inactivatingthe microbes, sterilizing the surface and if needed removing themicrobes and the organics from the surface by plasma ashing using oxygengas mixture in the plasma. The presence of multiple inlets, dual plasmazone, plasma gradient and temperature gradient properties canefficiently be used to bombard the cell structure of the microbes,change its morphology and also surface chemistry whereby inactivatingthe microbe. Further intense plasma treatment can be used to remove andvaporize the intra cellular components of the cell like that of aminoacids, proteins etc., and the cell structure whereby causing completeorganic decontamination from the surface.

The adjustable electrodes can be placed close to the nozzle such thatthe active plasma region is close to the surface being treated and theenergetic bombardment of the plasma generated species causing physicaldistortion of the cell structure and the presence of any oxygen speciesor any other reactive gas species changing the surface chemistry of thecell structure and cellular components providing dual impact of physicaldistortion and chemical structure change on the microbes resulting ininactivation. Prolonged treatment of the surface or treatment withappropriate gas mixture like that of oxygen and argon for example couldcompletely remove the cellular debris paving way for dual benefit ofinactivating microbes and removing the cell debris and organiccomponents of the cells from the surface being treated.

Some features and advantages of the invention have been generallydescribed in this summary section; however, additional features,advantages, and embodiments are presented herein or will be apparent toone of ordinary skill in the art in view of the drawings, specification,and claims hereof. Accordingly, it should be understood that the scopeof the invention is not limited by the particular embodiments disclosedin this summary section.

A printing apparatus containing a modular assembly of a plasma jet printhead with multiple removable, adjustable and replaceable modules fordirecting and printing materials in a defined geometry with desiredmaterial properties by sustaining a stable arc less plasma inside adielectric tube.

The apparatus comprises: a dielectric tube containing two or moreelectrodes on its outer side that are connected to a high voltage powersupply, to generate a plasma inside the dielectric tube in the presenceof a gas, that avoids arcing both inside the dielectric tube as well asoutside the dielectric tube between the electrodes and avoids arcingbetween the print head and coated material/substrate/substrate holder,and that accelerates, directs the aerosolized materials from a nebulizerin a geometrical fashion, with minimal loss of materials to the wall ofthe dielectric tube resulting in high density of materials directedthrough the nozzle; detachable dielectric tubes connected together whoseone end is connected to a manifold through which the carrier gas andmaterial to be printed are introduced in aerosol form, the other end hascontinuously reducing inner diameter to form a nozzle that is detachableand replaceable with an orifice through which materials from the tubewill exit in a defined geometry, central portion of the tube containingelectrodes; the detachable tubes are made of dielectric material, thenozzle can be made of same dielectric or different dielectric ormetallic material or a combination of dielectric and metal to avoidarcing between the plasma and the coating or substrate or substrateholder and by enabling precise delivery of the material out of the printhead for controlled geometrical printing;

The orifice diameter in the detachable nozzle can be varied to controlthe geometry of printing and resolution while the diameter of thedielectric tube can either be fixed or varied and the material to beprinted is accelerated out of the nozzle with a momentum created by theexternally applied electric field, plasma and gas pressure, to enablefocused expulsion of the material from the dielectric tube through thenozzle towards a substrate for printing;

The inner portion of the detachable nozzle can contain metal layereither connected to ground or in floating potential to avoid arcingbetween the print head and the substrate or substrate holder; multiplemovable metal electrodes to change the spacing between the electrodes,dispersed at the inlet, outlet or along the outer circumference of thedielectric tube and connected to high voltage power source to generateplasma, an active plasma region, with desired plasma characteristicsthrough controlled electrode area, spacing of electrodes and itsconfiguration depending on required resultant material characteristics;each electrode having a dielectric encapsulation with the thickness ofthe encapsulation dielectric being more than thrice the thickness of thedielectric tube used to generate plasma.

Each electrode of the print head/apparatus described herein may have adielectric encapsulation. In some embodiments, the dielectricencapsulation may have a thickness that is less than, equal to, orgreater than the thickness of the dielectric tube that the electrode isattached to. In some embodiments, the dielectric encapsulation has athickness that is greater than the thickness of the dielectric tube. Insome cases, the dielectric encapsulation has a thickness that is atleast twice the thickness of the dielectric tube. In some cases, thedielectric encapsulation has a thickness that is at least three timesgreater than the thickness of the dielectric tube. In some cases, thedielectric encapsulation has a thickness that is at least four timesgreater than the thickness of the dielectric tube. In some cases, thedielectric encapsulation has a thickness that is at least five timesgreater than the thickness of the dielectric tube. When a dielectricencapsulation has a greater thickness than the thickness of thedielectric tube, arcing between the electrodes is reduced. In somecases, arcing between the electrodes is eliminated. In some cases,arcing between the electrodes within the dielectric tube is reduced orprevented.

In some cases, arcing can be reduced or prevented by using a dielectricmaterial in the dielectric encapsulation that is different from thedielectric material in the dielectric tube. In some embodiments, thedielectric material of the dielectric encapsulation has a higherdielectric strength than the dielectric material of the dielectric tube.As the dielectric strength varies with the thickness of the dielectricmaterial, the thickness, geometry, or both, of the dielectricencapsulation and/or dielectric tube can be adjust to maximize thecorresponding dielectric strength accordingly.

In some embodiments, the dielectric strength of the dielectric tube isabout 5 kV/mm to about 20 kV/mm. In some embodiments, the dielectricstrength of the dielectric tube is at least about 5 kV/mm. In someembodiments, the dielectric strength of the dielectric tube is at mostabout 20 kV/mm. In some embodiments, the dielectric strength of thedielectric tube is about 5 kV/mm to about 7.5 kV/mm, about 5 kV/mm toabout 10 kV/mm, about 5 kV/mm to about 12.5 kV/mm, about 5 kV/mm toabout 15 kV/mm, about 5 kV/mm to about 17.5 kV/mm, about 5 kV/mm toabout 20 kV/mm, about 7.5 kV/mm to about 10 kV/mm, about 7.5 kV/mm toabout 12.5 kV/mm, about 7.5 kV/mm to about 15 kV/mm, about 7.5 kV/mm toabout 17.5 kV/mm, about 7.5 kV/mm to about 20 kV/mm, about 10 kV/mm toabout 12.5 kV/mm, about 10 kV/mm to about 15 kV/mm, about 10 kV/mm toabout 17.5 kV/mm, about 10 kV/mm to about 20 kV/mm, about 12.5 kV/mm toabout 15 kV/mm, about 12.5 kV/mm to about 17.5 kV/mm, about 12.5 kV/mmto about 20 kV/mm, about 15 kV/mm to about 17.5 kV/mm, about 15 kV/mm toabout 20 kV/mm, or about 17.5 kV/mm to about 20 kV/mm. In someembodiments, the dielectric strength of the dielectric tube is about 5kV/mm, about 7.5 kV/mm, about 10 kV/mm, about 12.5 kV/mm, about 15kV/mm, about 17.5 kV/mm, or about 20 kV/mm. In some cases, thedielectric tube comprises alumina and has a dielectric strength of about13.4 kV/mm.

In some embodiments, the dielectric strength of the dielectricencapsulation is about 15 kV/mm to about 30 kV/mm. In some embodiments,the dielectric strength of the dielectric encapsulation is at leastabout 15 kV/mm. In some embodiments, the dielectric strength of thedielectric encapsulation is at most about 30 kV/mm. In some embodiments,the dielectric strength of the dielectric encapsulation is about 15kV/mm to about 17.5 kV/mm, about 15 kV/mm to about 20 kV/mm, about 15kV/mm to about 22.5 kV/mm, about 15 kV/mm to about 25 kV/mm, about 15kV/mm to about 27.5 kV/mm, about 15 kV/mm to about 30 kV/mm, about 17.5kV/mm to about 20 kV/mm, about 17.5 kV/mm to about 22.5 kV/mm, about17.5 kV/mm to about 25 kV/mm, about 17.5 kV/mm to about 27.5 kV/mm,about 17.5 kV/mm to about 30 kV/mm, about 20 kV/mm to about 22.5 kV/mm,about 20 kV/mm to about 25 kV/mm, about 20 kV/mm to about 27.5 kV/mm,about 20 kV/mm to about 30 kV/mm, about 22.5 kV/mm to about 25 kV/mm,about 22.5 kV/mm to about 27.5 kV/mm, about 22.5 kV/mm to about 30kV/mm, about 25 kV/mm to about 27.5 kV/mm, about 25 kV/mm to about 30kV/mm, or about 27.5 kV/mm to about 30 kV/mm. In some embodiments, thedielectric strength of the dielectric encapsulation is about 15 kV/mm,about 17.5 kV/mm, about 20 kV/mm, about 22.5 kV/mm, about 25 kV/mm,about 27.5 kV/mm, or about 30 kV/mm.Arcing between the electrodes mayalso be prevented by using electrodes in which the electrodes havedifferent surface area. In some cases, the surface areas of theelectrodes differ by a factor of 2, 3, 4, or 5. In some embodiments, theprint head described herein comprises a first electrode and a secondelectrode, wherein the first electrode has a surface area that isdifferent from the surface area of the second electrode. In some cases,the surface area of the first electrode may be greater than the surfacearea of the second electrode. In some cases, the surface area of thefirst electrode may be less than the surface area of the secondelectrode. In some cases, the dielectric encapsulation comprisespolytetrafluoroethylene (PTFE) and has a dielectric strength of about19.7 kV/mm.

In some embodiments, the metal electrodes each have uneven surface areaso as to avoid arcing by creating an extended electric field between theelectrodes on the inner side of the dielectric tube. In someembodiments, one of the electrodes has a perimeter/surface area that ismore than double that of the second electrode.

In some embodiments, one or more than one dielectric tubes are placedinside the dielectric tube. In those cases, the one or more dielectrictubes can be extended from inlet manifold up to nozzle. The length ofthe inner dielectric tube/tubes can be varied either to be short so thatthe material coming out of the tube is in the active plasma region andthe materials can be interacting with the plasma species. In some cases,the tube length can be extended all the way up to nozzle to avoidmaterial interaction with plasma species. The tube can also be made ofmetal and connected to electrical source or to ground and function as anelectrode.

Optional multiple electrodes dispersed over the primary dielectric tubethat can be connected to same or different voltage sources that providevarying input energy to multiple electrodes creating dual field in thedielectric tube and generating dual plasma zone. Multiple electrodesdriven by varying electrical energy inputs create a gradient plasma andhence a temperature gradient in the dielectric tube; a provision forintroducing the primary gas closer to the electrodes for igniting theplasma and if needed a carrier gas with a higher breakdown voltage beingused for transporting the aerosol to the plasma region so that theplasma is concentrated in between the electrodes and thereby avoidingpresence of plasma outside of the electrode region and minimizing lossof materials to the walls of the tube that connects the nebulizer to theprint head in the form of plasma deposition;

In some embodiments, the adjustable electrode configuration allows tochange the spacing between the electrodes without removing the electrodefrom the assembly to control process parameters like temperature, meanfree path/residence time in plasma, effective plasma area etc., to getspecific material properties

In some embodiments, the material to be printed is accelerated out ofthe nozzle by the externally applied electric field, plasma and gaspressure, with defined orifice to enable focused expulsion of thematerial from the dielectric tube towards a substrate for printing on adefined geometry.

In some exemplary embodiments, one configuration there may be one inputfor the precursor, or gas, to enter into the primary dielectric tube. Inanother configuration there may be a plurality of inputs for more thanone precursor, or gases, to enter the primary dielectric tube, eitherone at a time or simultaneously. In yet another configuration there maybe one or more inputs for the precursors, or gases, to enter into theprimary dielectric tube and there may be a secondary dielectric tubewithin the primary dielectric tube. In this configuration the precursorsmay enter into either the primary or secondary dielectric tube, or both,one at a time or simultaneously.

In some embodiments, the multiples electrodes can be dispersed inside,outside of dielectric, continuous, wound, embedded with dielectric etc.,

In some embodiments, the electrodes the dielectric tube could be made ofany aluminum, quartz, ceramic, teflon, machinable ceramic, macor etc. Insome cases, the electrodes comprise an electrically conducting material.In some cases, the electrodes are connected to one or more voltagesources. In some cases, the voltage sources comprise one of a DC source,a pulsed DC source, an AC source, an RF source, and a microwave voltagesource.

In some embodiments, the replaceable nozzle has provision forintroducing non-interactive sheath gas for focusing the materials comingout of the nozzle. In some cases, in the adjustable electrode spacing,uneven surface area of the electrodes, dielectric strength and thicknessof the dielectric tube and dielectric encapsulation, extreme appliedvoltage sources, gas mixtures and modular design of the inlet manifold,plasma manifold and nozzle manifold allows for intricate control ofplasma characteristics to print materials with high molecular precisionand required characteristics.

In some embodiments, the modular assembly can be used to treat materialsand/or microbes on the surface using appropriate gas mixtures andelectrode configuration, to make maximum possible impact to the targetsurface through a combination of energetic ion bombardment and reactivespecies generated in the plasma to change the morphology, topography,chemical structure, molecular structure, surface energy of the materialbeing treated and also to remove any organic molecules from the surface.

Another aspect of the invention provided herein relates to photonicsdevices, and more particularly, to plasma jet printing apparatus andmethod for printing optical materials with desired optical propertiesfor manufacturing of photonic and hybrid electronic photonics devices.

Printing of optical materials with tailored optical characteristics canhave far reaching applications in manufacturing of next generationphotonics-based devices. A wide variety of optical materials includingpolymeric materials, electro-luminescent materials and plasmonic metalmaterials are key elements in manufacturing of next generationcommunication and information systems, optical switching, computing, anddisplay panels—both organic light emitting diodes and photonic displays.

Traditional manufacturing methods are not always compatible with thenature and type of materials being explored or with the nature andgeometry of the substrate materials on which the optical materials arebeing printed.

There is a need for novel manufacturing technologies that can enableprinting of wide variety of optical materials on a range of substratesto allow low-cost and high-performance fabrication of optical devices.

With the rapid growth of Internet of Things, connected devices,telecommunications, and cloud computing, the bandwidth requirements ofdata centers and high-performance computers have increased drastically.All these factors are driving exponential growth in data, with aconsequent need to handle data densities and transfer speeds beyond thefunctional limits of metal interconnects. Power consumption, datatraffic congestion and noise become major issues. There is a need foroptical interconnection systems that are compatible with electronicsystems as a hybrid configuration. Embedded optical communicationschannels within computer systems could provide higher bandwidth capacityto satisfy the needs of the industry.

Advanced polymeric materials have been explored for non-linear opticsand optoelectronics applications. Organic-based components such asoptical waveguides, modulators, optical switches, splitters, organiclaser sources, optical amplifiers and detectors are all being heavilyresearched.

Optical waveguides made of optically transparent materials that canguide electromagnetic radiation in UV, Visible, and/or IR wavelengthranges can be used as components in integrated optical circuits.

Optical fibers and optical waveguides may be considered to make up twodifferent classifications of optical interconnects. According to thetype of material used to fabricate the waveguides, optical waveguidescan be classified as inorganic or organic. Inorganic waveguides areprimarily silicon dioxide-based and organic waveguides are primarilypolymer-based.

The higher bandwidth capacity, low noise, and low cross talk that arecharacteristic of polymer waveguides, along with their ability toincrease the channel density, make them highly attractive. Hence,board-level optical interconnects made of polymer waveguides are widelybeing explored. Polymer based devices offer low cost and a simpleprocess for fabrication.

Printing technologies enable fabrication of optical devices and theirintegration on to structural components.

Another variety of optical materials that can control light atnanometer-scale by coupling electromagnetic field to the oscillations offree electrons in metals includes plasmonic materials. Plasmonicnanoparticles such as colloidal silver and gold particles stronglyscatter and absorb light near to their localized surface plasmonresonance (LSPR).

For plasmonic coupling of electromagnetic waves to the free electroncloud of the metals, the metal film or structure that is used should besupported on a dielectric medium that has certain specific opticalproperties.

The plasmon resonance intensity and wavelength depend on the kind ofmetal, nanoparticle size and shape, as well as the dielectric strengthof the surrounding medium. Appropriate choices of these parametersprovide the capability to tune the plasmon resonance, which is crucialfor several applications, including plasmonic detection of biomolecules,particle-based therapies, nanoantennas etc.

The plasmonic surfaces prepared through printing of nanoparticles andmetamaterials have applications in optoelectronics, liquid crystaldisplays, touch screens, etc. Further development of plasmonicapplications relies on the emergence of new fabrication methods ofplasmonic devices.

Transparent conductive indium tin oxide (ITO) substrates are currentlyused to fabricate transparent electrodes in a large variety ofoptoelectronic devices including liquid crystal dis-plays, touchscreens, and organic light-emitting devices. Plasma jet printing ofplasmonic metal nanoparticles onto ITO substrates could play animportant role in creating future plasmonic and optoelectronic devices.

Thick metallic films perforated by arrays of sub wavelength holes cangreatly enhance the optical transmission of underlying waveguides. Ithas been reported that surface plasmon resonance is the primary reasonfor the extraordinary optical transmission of such waveguides.

Direct write printing technologies play a crucial role in printingplasmonic materials and engineered nanomaterials, also known asmetamaterials, with precise size, shape, geometry etc. Precisecontrolling of thickness, density of packing, particle size and shape,dielectric strength of the adjacent medium are all very important forplasmon resonance.

An important problem in optical packaging involves the opticalinterconnection of planar-integrated photonic integrated circuits suchas chip-chip connections, and the connection of such circuits to theexternal world. Photonic integrated circuits (PICs) refer towaveguide-based photonic components, including optical integrateddevices such as lasers, optical amplifiers, switches, filters,modulators, splitters, phase shifters, variable attenuators, detectors,and the like. PICs can also include integration with semiconductordevices such as CMOS electronic devices.

Various methods for manufacturing optical waveguides have been usedusing polymer materials. These methods include photolithography method,a hot embossing method, reactive ion etching, laser ablation, molding, adirect ultraviolet patterning method, a laser direct writing method,inkjet printing and aerosol jet printing, or a combination thereof. Anultraviolet (UV) curing approach involves applying UV radiation toresins or polymers to cause photo-polymerization. In aphoto-polymerization reaction, a monomer comprising a single organicunit, or an oligomer—a molecule comprising a small number of organicunits—is converted, or cross-linked, to form a solid cross-linkedpolymer.

The photolithography method includes very complicated processesinvolving multiple steps, including coating a cladding material on asubstrate, baking, coating a core material, applying photoresist,exposure using photomask, developing and etching.

In the hot embossing method, a core portion is molded in under-cladmaterial using a mold master, core material is inserted into the moldedstructure, an overclad is deposited there-on, and ultraviolet radiationis applied in order to cure the core material and adhere the over clad.

In the ultraviolet direct patterning method, after an underclad isformed on a planar substrate, a ultraviolet-curable polymer is coatedthereon as a core layer. Then, after ultraviolet exposure through aphotomask, a core pattern is formed by using a polymer developer, andfinally, a coating of an upperclad material is applied.

The laser direct writing method is based on a laser micro-machiningtechnique. The laser direct writing method has the advantages of a shortprocess time, low cost and the possibility of application over a largearea, because of the simplicity of the process, without the need for aphotomask.

Plasma jet printing can either be used as an alternative to inkjetprinting, spin coating, screen printing, dipping, spraying, or incombination with one or more than one of these printing technologies asa complementary technique for printing certain types of materials.

Plasma jet printing provides an alternative strategy to achieve fastselective deposition of plasmonic nanoparticles onto transparentconductive electrode substrates.

Embodiments of the current invention described in this disclosure useplasma jet printing as a novel way of fabricating optical packaging, inparticular in fabricating optical polymer waveguides.

Waveguide performance depends strongly on the quality of the waveguidesurfaces, such as the core sidewalls. High surface roughness or defectsbecome the strongest contributor to op-tical scattering loss along alow-quality waveguide

Refractive index changes can also severely affect the quality ofwaveguides and device performance. Plasma jet printing process enablestailoring surface roughness and refractive index.

Optimizing the plasma printing process parameters is essential inachieving high trans-mission quality and high resolution. Plasma jetprinting enables manufacturing of both single mode and multimodewaveguides.

Silicon dioxide (silica) is an important material for a range ofapplications. For example, silica can be used to form transparentoptical materials useful for the transmission of light. In addition,silicon dioxide is a useful dielectric for applications in electronicsand plasmonics. Also, silicon dioxide can be selectively doped toinfluence the properties.

In the fabrication of optical waveguides for optical communications,silica particles or a silica film can be printed to form waveguidesusing a plasma jet process. The index of refraction of the resultingoptical waveguide structure can be altered through plasma processcontrol to get a desired refractive index profile or distribution, forexample, a uniform refractive index, or a continuously varyingrefractive index, or a profile with a sharply defined lateral and/orlongitudinal boundary.

Other applications include displays in which display elements can beformed through the disclosed printing process and subsequent processing.The printing process can be effective to form display structures with adesired optical material at selected locations within the structure,wherein the optical materials incorporate particular dopants toinfluence the optical and/or other physical properties of the material.

Fluorescent or luminescent materials like phosphor particles can becoated with silica either in solution or during plasma printing. Boron,phosphorous and/or germanium dopants can be added as plasma processparameters. Plasma jet printing can be used to print active materialsthat can emit light under appropriate activating conditions.

Plasma jet printing provides the ability for effective printing ofsilicon dioxide with or without dopants to form structures at higherresolution than what other currently used methods allow. Withappropriate control of plasma process parameters, the silicon dioxidecan be printed rapidly and with relatively high resolution. The abilityto introduce selected dopants over a wide range of compositions providesthe ability to form a correspondingly wide range of devices based onproperties of the silicon dioxide film or particles used.

Plasma jet printing allows for fast and programmable deposition ofnumerous colloidal plasmonic metal nanoparticles onto a transparentelectrode, along arbitrary 2D circuits that can be easily designed.

Plasmons may be created in graphene, providing a material with manyunique properties and allowing for practically useful methods of lightmanipulation. Such graphene plasmons can have far reaching applicationsin computing and in displays. The tunable plasmonic characteristics ofgraphene on its own as well as the combination of graphene plasmonicswith noble metal nanostructures offer a wide range of applications thatare not easily achieved by conventional noble metal plasmonics withoutgraphene.

The versatility of graphene means that graphene-based plasmonics mayenable the manufacture of novel optical devices working in differentfrequency ranges, from about 0.5 terahertz to about 300 terahertz, withextremely high speed, low driving voltage, low power consumption andcompact sizes. Graphene plasmons at mid-infrared and longer wavelengthsare known. Controlled doping may allow them to be created in the visibleand near-infrared regimes.

The use of the plasmon resonance characteristics of aluminumnanoparticles for color displays has already been explored. The displaysare made up of arrays of pixels which are made up of nanostructures, andthe color is generated by the characteristics of light scattered.Different arrangements create different colors. Aluminum plasmonicpixels are advantageous for use in electronic displays because they areinexpensive and can be made in an ultra-small size, which can increaseimage resolution.

Several approaches have been reported so far to create patternedstructures using graphene oxide (GO) ink, including micromolding incapillaries (MIMIC), gravure printing, screen printing and inkjetprinting. The first two suffer from limited scalability while screenprinting has the lowest resolution among all techniques. Hence, inkjettechnology is the most accepted choice for the fabrication of suchdevices.

However, present inkjet printing technologies, widely used to printgraphene based electronic devices, suffer from the need for various postprocessing steps, and are also substrate dependent. The major issue withGO-based inks is the need for reduction after printing, which is doneeither by high temperature annealing or by reducing agents likehydrazine vapor. Other techniques include UV reduction and annealing inan Argon/Hydrogen atmosphere.

Tailoring the ink plays a key role for a successful printing process.Ink properties like viscosity, surface tension and density are importantand need to be designed according to the substrate. Most inks, includinggraphene inks, require sophisticated pre-and post-processing steps.Thus, there is a strong drive to develop a robust technique that isindependent of the ink in use and has the ability to perform anyadditional processing steps in-situ. Plasmas, whether at low pressure orespecially at atmospheric pressure, possess considerable potential infunctionalization of carbon based materials. This is because plasmadischarges can allow the fixation of different chemical species of thesame element to the graphene structure. Atmospheric pressure plasma jetprinting could, therefore, be an ideal solution to overcome severalproblematic issues of conventional printing techniques.

As described in detail herein, plasma jet printing of reduced grapheneoxide with He and H₂ plasma can simultaneously deposit graphene oxidefrom a highly acidic precursor and reduce it. The deposited films can befurther treated with plasma to enhance their properties. This processeffectively negates all the intermediate steps involved in wetchemistry-based preparation. The removal of oxygen functionalities isexpected to have a definite effect on the electronic properties of thegraphene oxide films.

A plasma jet process can reduce in situ highly acidic graphene oxidewithout the need for external post-processes. No other printingtechnique has achieved this till now. The reaction intermediatesotherwise formed during synthesis of graphene oxide can be eliminated byintroduction of reducing gases in the plasma. This reduction processaids in the recovery of the sp2 structure of the graphitic lattice.

According to one aspect of the present invention, there is provided anapparatus for direct write, dry printing and patterning of opticalmaterials using plasma jet with tailored optical properties to fabricatephotonics and hybrid photonics devices. The materials can be printed ona single layer or as multiple layers. Printing can be either as ahomogeneous material or as a hybrid film containing one or more than onetype of material, or more than one variation of same material. Uses ofthe fabricated devices include but are not limited to communication andinformation systems, optical packaging, computing, and display panels.The methods and apparatus described herein can facilitate printing ofmulti-materials such as organics, inorganics, plasmonics etc., withtailored material characteristics as a homogeneous or as a hybrid film.

One apparatus comprises a modular print head for generating plasma thatenables direct write dry printing. In some embodiments, the print headcomprises an inlet module to allow one or more than one opticalmaterials, and/or one or more than one gas mixture into the print headand the plasma region. In some embodiments, the modular print headcomprises a nozzle containing an orifice for printing the materials. Insome embodiments, a mask can be attached to the print head forpatterning of the optical materials. The mask can be moved together withthe print head or moved independently using a piezo motor, or some othermeans of creating relative motion. The piezo motor or other meansattached to the mask, so that the entire print head can remainstationary while the mask moves to create a pattern.

The mask can be manufactured using any of a number of known methods,like photo lithography, silicon micromachining, photo chemicalmachining, precision machining, plasma etching, reactive ion etching, ora combination thereof The mask can enable printing feature sizes inmicron or sub-micron geometries that are not achieved by other printingmethods such as ink jet, aerosol jet, screen printing, or a combinationthereof. The mask can be attached to the modular assembly of the printhead at the outlet of the nozzle so that the mask can be removed andreplaced as necessary, depending on the required feature size inprinting and also depending on the nature of material.

In one embodiment, an inlet of the modular print head contains anatomizer or nebulizer that creates an aerosol mist from the materialthat enters the print head through the inlet. In some cases, theatomizer or nebulizer creates an aerosol mist of a colloid-containingoptical material. In some cases, the atomizer or nebulizer creates anaerosol mist of a precursor/monomer that can be polymerized by plasma ora polymeric blend. In some cases, the atomizer or nebulizer can beoperated pneumatically. In some cases, the atomizer or nebulizer can beoperated by a piezo electric method that allows the particle size to bepredetermined using appropriate values of gas flow and piezoelectricoperating frequency. Either one material may be introduced, or multiplematerials may be introduced simultaneously, to create a homogeneous orheterogeneous or hybrid film. For the multiple material cases, more thanone gas supply may be attached to the inlet through mass flowcontrollers. The one or more gases are used to generate plasma anddepending on the need, a reducing gas or an oxidizing gas or any otherchemical reactive gas or gas mixtures can be used to tailor the opticalproperties of the material being printed. The gas and liquid precursorinlet can also be used to pretreat the substrate and/or to post-treatthe printed pattern. In one embodiment, the apparatus, the modular printhead, can also be used as a plasma etcher to etch materials from asurface. The same inlet can also be used to clean the print head byintroducing appropriate gas mixtures and/or liquid precursors that willbe used to etch or remove the materials settled in the inner part of thedielectric tube during printing, effectively cleaning the nozzle and theprint head.

Either the print head or the mask can be moved in such a way that one ormore chemical gradients are created, and optical properties may bevaried, either continuously or discontinuously, to produce discreteunits of materials with defined optical properties. Boundaries can bedefined using a combination of print head or mask movement and carefulcontrolling of input materials and gas mixtures.

The print head may also have the ability to control the size and shapeof the orifice such that the geometry of the printed material can bemodified in situ. One such method of orifice size and shape controlinvolves two individual plates in sliding contact that have a shapednotch machined into the leading edge such that when one plate moves inrelation to the other it changes the size and shape of the orifice. Thisrelative motion may be controlled with a piezo motor, a stepper motor orsimilar. Varying the size and shape of the orifice while printingprovides an additional method of controlling the printed materialgeometries and cross sectional profiles.

Plasma jet printing of silicon dioxide (silica) can be carried outeither using ink containing silica nanoparticles or by plasmapolymerization of organosilane or siloxane precursors. In the case ofsilica nanoparticles, the surface chemistry can be changed either viathe liquid solution by mixing appropriate reactants or via the plasmaprocess by introducing an appropriate gas mixture or mixtures to modifynanoparticles' surfaces. In the case of plasma polymerization oforganosilane or siloxane, the film chemistry and the refractive indexcan be changed by introduc-ing appropriate gas mixtures or reactants inthe print head.

In the latter case, the surface modification agent such as a gas mixtureor a reactant, can be introduced into the print head. The degree ofsurface modification and the degree of polymerization can be controlledby selection of the corresponding plasma process parameters. In somecases, introducing a carbon-based or fluorine-based source, whileprinting silicon dioxide, can produce low K dielectric films. In somecases, introducing nitrogen can produce high K dielectric films. In acase where a silica coating is formed by plasma polymerization of asiloxane precursor, controlling the oxygen flow rate into the print headcan result in a film with varying carbon content and refractive index.

In some embodiments, using graphene oxide, a reducing gas like hydrogenor ammonia can be introduced into the print head so that the grapheneoxide is reduced in-situ and the printed pattern contains reducedgraphene oxide.

In some cases, the output of the plasma jet printing process is a drymaterial that is printed onto the substrate. Compared to the mainalternative, this removes both the curing step and the spreading ofliquid droplets that could affect the resolution and line width.Relatively quick, cheap and easy manufacturing of optical waveguides cantherefore be achieved with plasma jet printing.

FIG. 13 shows a cross sectional view of an exemplary plasma print head 1containing precursor and gas inlet module 100, plasma modules 200 a and200 b, and nozzle module 300, all of them within an enclosure 400. Theplasma print head aerosolizes the materials, mixes aerosolized materialand gas mixtures at the inlet manifold, generates plasma to direct,accelerate and/or process the materials entering the print head andprint with defined resolution onto the substrate placed outside themask. The inlet module 100 comprises an inlet manifold 110, throughwhich liquid precursors, aerosolized ink and gas mixtures are introducedand mixed. The inlet module 100 is made of a dielectric material, andcontains gas mixing inlets 121 and 122, and atomizer/nebulizer 123 thataerosolizes the liquid (precursor or monomer or polymer or liquid orink, hereafter called a “liquid precursor”) entering the atomizer andgas mixing inlets 121 and 122. The inlet module is attached to adielectric tube 210, and to the plasma modules 200 a and 200 b which inturn are connected to nozzle module 300, all of which can be dismantledand connected together depending on the required plasma characteristicand the type/quality of materials being printed.

In FIG. 13, inlet module 100 comprises an atomizer/nebulizer 123 thatgenerates an aerosol of the material to be printed; and a plurality ofgas inlets 121 and 122, all connected to inlet manifold 110. Thedielectric inlet manifold 110 also comprises an opening 130 whichconnects the primary dielectric tube 210 to the inlet manifold. In somecases, the dielectric inlet manifold 110 also comprises an optionalsecondary dielectric tube 140, as shown in FIG. 14A. The electrodes 221and 231 are attached to the dielectric tube 210. One of the electrodescan be connected to the positive terminal of the power supply, andanother can be connected to the negative or ground terminal. In somecases, additional electrodes can be placed depending on the need.

The inlet manifold 110 can hold a cluster of tubes (not shown in thefigure) or have a cluster of inlets 120, 121, and 122. Each inlet can beused to introduce one or more gases, one or more precursors, one or morematerials or one or more gas mixtures. In some cases, each inlet canconnect one or more secondary dielectric tubes that are placed insidethe primary dielectric tube.

In some embodiments, all the inlets 120, 121 and 122 can be connected togas supply lines. In some embodiments, as shown in FIG. 14A, one of theinlets can be connected to an atomizer or nebulizer 123 that cangenerate an aerosol mist of liquid entering the nebulizer.

In some embodiments, as shown in FIG. 14B, the inlet manifold 110 can beof sufficient size and volume so that the atomizer or nebulizer can bemounted inside the inlet module.

In some embodiments, as shown in FIG. 14C, the inlet manifold 110 canhave more than one atomizer or nebulizer, 123 and 124, for aerosolgeneration so that two different liquid precursors can be introducedinto the print head. In some cases, the two nebulizers 123 and 124 canbe of similar type. In other cases, each one can function differently.For example, nebulizer 123 can be a pneumatic nebulizer, and nebulizer124 can be a piezoelectric nebulizer, both can be pneumatic nebulizers,or both can be piezoelectric nebulizers.

The piezoelectric nebulizers can be operated at similar or varyingfrequencies depending on the need. In some cases, the frequency is about0.05 MHz to about 10 MHz. In some cases, the frequency is at least about0.05 MHz. In some cases, the frequency is at most about 10 MHz. In somecases, the frequency is about 0.05 MHz to about 0.1 MHz, about 0.05 MHzto about 0.5 MHz, about 0.05 MHz to about 1 MHz, about 0.05 MHz to about5 MHz, about 0.05 MHz to about 10 MHz, about 0.1 MHz to about 0.5 MHz,about 0.1 MHz to about 1 MHz, about 0.1 MHz to about 5 MHz, about 0.1MHz to about 10 MHz, about 0.5 MHz to about 1 MHz, about 0.5 MHz toabout 5 MHz, about 0.5 MHz to about 10 MHz, about 1 MHz to about 5 MHz,about 1 MHz to about 10 MHz, or about 5 MHz to about 10 MHz. In somecases, the frequency is about 0.05 MHz, about 0.1 MHz, about 0.5 MHz,about 1 MHz, about 5 MHz, or about 10 MHz.

In some embodiments, the print head comprises at least two plasmamodules 200 a and 200 b; each plasma module contains a plasma manifold:plasma manifolds 220 and 230, respectively. In some cases, each plasmamodule contains an electrode: electrodes 221 and 231. The electrodes areconnected directly to the circumference of the primary dielectric tube210. In FIG. 13, the electrodes 221 and 231 surround dielectricenclosures 222 and 232, respectively. Also in FIG. 13, the plasmamanifold 200 is shown as containing an electrical feedthrough 224connected to the electrode 221 within dielectric encapsulation 222.

The electrodes 221 and 231 in the plasma manifolds are fixed to theprimary dielectric tube 210 using adjustable mechanical positioncontrollers 225 and 235, respectively.

In some embodiments, the position controller can be a screw, slide or bemade of any adjustable fixture. In some cases, the position controllercan be moved along the axis of the primary dielectric tube 210 by manualmeans or by using a mini motor. The spacing between electrodes 221 and231 can be controlled using the position controllers 225 and 235,respectively, depending on the nature and type of materials beingprinted and the plasma characteristics needed to obtain molecularprecision in printing.

FIG. 15 is a cross sectional view of an exemplary nozzle module 300 withan internal orifice diameter 310. In this exemplary embodiment, anorifice controller or mask 302 is connected to the piezo motor 301 whichis placed in the enclosure 400. The orifice controller or mask 302 canbe independently moved with respect to primary dielectric tube 210. Insome cases, the orifice controller or mask can also be moved togetherwith primary dielectric tube 210. The mask can have features in themicron or sub-micron range, and it can enable fine geometry printingthat is not otherwise possible without the mask. An example of afine-geometry printing pattern 352 is shown on substrate 353.

FIG. 16 is a cross sectional view of the modular portion of an exemplaryplasma module 230. In this embodiment, the plasma module contains thedielectric tube 210 that is connected directly to the orifice controlleror mask 302.

FIG. 17 shows an exemplary configuration of the printing apparatus, inwhich the plasma print head 1 can be used in combination with othertypes of printer 500. In some cases, the other type of printer is anaerosol jet printer. In some cases, the other type of printer is an inkjet printer. The plasma module can be attached directly to the printhead 501 of the non-plasma printer comprising ink jet, aerosol jet, coldspray or a combination thereof. In some embodiments, the print head ofthe non-plasma can be attached to the print head of the plasma printerwithout the orifice controller or mask 302 and/or piezo motor 301. Inother embodiments, the print head of the non-plasma printer can beattached to the print head of the plasma printer without the inletmodule 100.

FIG. 18 is a three-dimensional view of an exemplary print head with anenclosure containing the electrodes, electrode encapsulations and highvoltage cable connections.

FIG. 19 is a photograph of an exemplary print head comprising anatomizer/nebulizer, an inlet manifold, a dielectric tube with electrodesand high voltage cable, and an enclosure enclosing the portion ofdielectric tube.

FIG. 20 is a photograph of the lower portion (outlet/printing) of anexemplary print head showing a dielectric tube with electrodes enclosed,and an enclosure with plasma jet shown at the bottom.

FIGS. 21 provide exemplary top views of embodiments of the orificecontroller or the mask showing patterned printing and ability to adjustorifice size, shape and printing resolution without having to replacethe nozzle. Parts 302 a and 302 b comprise two parts of the orificecontroller which can be moved independently to control the pattern 303 aand printing resolution. FIGS. 21A, 21B and 21C show differentembodiments of the mask in which three different printing patterns 303a, 303 b and 303 c are obtained by adjusting 302 a, 302 b, and 302 c,respectively. Three different printing patterns 352 a, 352 b and 352 cwere obtained using a single mask assembly.

FIG. 22 is cross sectional view of an exemplary nozzle module 300 withorifice diameter 310. The orifice in nozzle module can be designed insuch a way that the axis of the nozzle orifice can vary from 0° to 179°with respect to the axis of the dielectric tube 210 (not shown in FIG.22). The orifice angle in the nozzle module can be varied to allow theprinting material to exit at different angles relative to the normalincidence angle of 90° relative to the substrate.

Described herein is a modular print jet apparatus for direct write dryprinting of one or more materials using atmospheric pressure plasma jet.In some cases, one or more properties of the one or more material aretuned using gaseous plasma and a mixture of precursors and gas mixturesin the plasma print head.

In some embodiments, the plasma jet apparatus comprises a plasma printhead. In some cases, the plasma print head comprises: a dielectric tubewith one end connected directly to an atomizer or nebulizer placed inclose proximity through an inlet manifold, and a second end connected toa nozzle; two or more electrodes being disposed over the outer side ofthe dielectric tube and connected to a shielded high voltage cable andpower supply to generate plasma discharge inside the primary dielectrictube; a nebulizer connected to one or more liquid precursor sourcescontaining a polymeric optical material, a plasmonic optical material,or a combination, to be printed, attached directly to the print headusing an inlet manifold connecting one end of the dielectric tube; aremovable, replaceable and independently movable mask connected to apiezo motor placed at the outlet of the nozzle such that material comingout of the dielectric tube is focused by the mask onto the substrate; anenclosure containing: a temperature sensor for measuring the temperatureof the primary dielectric tube for in-situ monitoring and optimizationof the plasma, an electromagnetic interference shielding mesh to preventelectromagnetic interference from the plasma print head affectingadjacent electronics, provision to place other sensors in closeproximity to the dielectric tube; the dielectric tube, the two or moreelectrodes, the high voltage cable; and a piezo motor with mask, inletmanifold, and nebulizer for generating aerosol mist; and multiple fluidconnections to the print head to introduce materials with similar orvarying optical properties and gas into the print head.

Described herein is a plasma jet apparatus for direct write dry printingof optical and plasmonic materials using atmospheric pressure plasmajet, in which the material properties are tuned using gaseous plasma anda mixture of precursors and gas mixtures in the plasma print head, tofabricate photonics and hybrid electronic photonic devices. In someembodiments, the plasma jet apparatus comprises a plasma print headcomprising: a dielectric tube with one end connected directly to anatomizer or nebulizer placed in close proximity through an inletmanifold and a second end connected to a nozzle, two or more electrodesbeing disposed over the outer side of the dielectric and connected to ashielded high voltage cable and power supply to generate plasmadischarge inside the dielectric tube; a nebulizer connected to one ormore liquid precursor sources containing the polymeric and or plasmonicoptical materials to be printed, attached directly to the print headusing an inlet manifold connecting one end of the primary dielectrictube; a removable, replaceable and independently movable mask connectedto a piezo motor placed at the outlet of the nozzle such that thematerials coming out of the dielectric tube is focused by the mask tothe substrate; an enclosure containing a temperature sensor formeasuring the temperature of the primary dielectric tube for in situmonitoring and optimization of the plasma, an electromagneticinterference shielding mesh to prevent electromagnetic interference fromthe plasma print head to adjacent electronics, provision to place othersensors in close proximity to dielectric tube, wherein the enclosureencloses the dielectric tube, electrodes and high voltage cables, piezomotor with mask, inlet manifold, nebulizer for generating aerosol mist;multiple fluid connection to the print head to introduce materials withsimilar or varying optical properties and gas into the print head.

In some embodiments, the atomizer or nebulizer is connected to one ormore than one liquid precursor source containing the monomer or polymeror plasmonic optical materials to be printed and the atomizer isattached directly to the print head using an inlet manifold connectingone end of the primary dielectric tube.

In some embodiments, the atomizer is attached directly to the dielectrictube of the print head can be used to generate an aerosol of the liquidprecursor and vary the diameter and volume of aerosolized liquiddroplets, wherein the liquid precursor can be a precursor or monomer orpolymer or colloid or ink.

In some embodiments, the atomizer can be a pneumatic atomizer or piezoelectric atomizer that creates an aerosol mist of the liquid that isintroduced into the atomizer. Depending on the required aerosol dropletsize, nature and viscosity of liquids, the appropriate atomizer can bechosen. In some cases, the atomizer is a piezo electric nebulizer andthe operating frequency can be independently controlled such that thedroplet size and volume of the aerosol carrying optical materials isoptimized for plasma jet printing.

In some embodiments, there can be more than one print head assemblyincluding a nebulizer, an inlet manifold, a primary dielectric tube, asecondary dielectric tube, a nozzle, a mask, or a combination thereof,that can be used to print polymeric and or plasmonic materialsindividually.

In some embodiments, the enclosure can contain two or more dielectrictubes. In some cases, one or more of the two or more dielectric tubescan be used to generate plasma discharge.

In some embodiments, the materials to be printed can be directed to thesubstrate through an orifice in the nozzle of the dielectric tube.

In some embodiments, a removable and replaceable mask is attached to theprint head through the enclosure and is placed close to the orifice ofthe dielectric tube such that a pattern can be printed. In some cases,the mask is connected to a piezo motor and moved independently withrespect to primary dielectric tube. In other cases, the mask is movedalong with the primary electric tube to draw patterns of materials ontothe substrate. The drawing of pattern can be by printing, plasmaetching, plasma curing, or a combination thereof, of materials.

In some embodiments, the gas flow inlet to the print head is through theinlet manifold.

In some embodiments, the plasma print head allows for variables forcontrolling plasma process parameters through one or more of thefollowing: externally applied voltage to the electrodes, gas flow rateand gas flow ratio of different gas mixtures, aerosol flow of liquid,flow rate of liquid to the nebulizer, working distance between the maskand substrate, primary dielectric tube diameter, orifice diameter,electrode separation, mask, or a combination thereof.

In some embodiments, the plasma print head allows in situ processcontrol such that the resulting printed films properties can beprecisely controlled. These properties can include film thickness, linewidth, aspect ratio, surface roughness, refractive index, opticaltransparency, plasmonics, dielectric strength, or a combination thereof.

In some embodiments, the plasma print head allows in situ doping whilethe printing is carried out and also allows more than one gas orprecursor materials to increase or decrease the dielectric strength byvarying the plasma process parameters or by creating porous structure.

In some embodiments, the polymeric optical material can be printed withappropriate plasma processing parameter to get any of the following:pristine optical property as is in the solution, tailored opticalproperty with appropriate gas mixture, doped polymeric optical film,hybrid polymeric optical and plasmonic film. In some cases, the opticalproperties can be refractive index, dielectric strength, transparency,optical transmission characteristics, or a combination thereof.

In some embodiments, the material to be printed is printed in a dry formwith specific line width resolution and aspect ratio by avoidingspreading of liquid droplets and by avoiding any post treatment needs.

In some embodiments, the plasma print head comprises one or more inletsconnected to gas, and one or more inlets connected to nebulizer foraerosol generation. In some cases, the one or more gas inlet can be usedfor pre-treatment of surfaces, etching, curing and or polymerization ofthe printed material or the surface.

In some embodiments, the plasma jet print head comprises a nebulizer, aninlet manifold, a dielectric tube with electrodes and enclosure, anozzle, a mask, or a combination. In some cases, the plasma jet printhead can be mounted on a XYZ stage. The stage may have an additionalability on which the workpiece (substrate) can be located on the stage.The stage may rotate around the Z-axis, or on a multi-axis robot toprint optical, photonics, plasmonic, electronic hybrid materials on aplanar or non-planar surface including 3D objects, flexible substrates.

In some cases, the print head itself may be able to rotate such that theresultant angle of incidence of the plasma jet relative to the substratemay be varied in a controlled manner from any angle between 90 degreesand 0 degrees, in either direction. In some cases, the print head mayrotate a full 360 degrees relative to its normal operating orientation,thus allowing printing in any direction. The combination of motion inthe X-axis, Y-axis, and Z-axis with the additional axis of rotationaround the Z axis and the ability for the print head to rotate relativeto the angle of incidence to stage on which the workpiece (substrate) islocated enables printing in any direction on 2D or 3D workpieces(substrates). Further, when the ability to articulate the print headrelative to the workpiece (substrate) is combined with the ability tomodify the size and shape of the print head orifice, an exceptionallevel of control over the geometry and cross sectional thickness of theprinted material can be achieved.

In some embodiments, the nozzle assembly within the plasma jet printhead may be substituted with a nozzle assembly that has a defined orchangeable curvature such that the direction of the materials such asplasma, gas and material used to print, exiting the print head may bechanged relative to the orientation of the print head such that printingmay be performed within complex structures that the print head assemblywould not be able to access

In some embodiments, the plasma jet print head can be integrated withother printing equipment including additive manufacturing equipment, anink jet printer, an aerosol jet printer, a cold spray, a plasmatreatment system, or a combination thereof. In some cases, the plasmajet printing can be done in parallel with or in series with othermanufacturing technologies. This will enable in-line manufacturing andembedding of plasma jet printed materials onto any other structuresbeing manufactured.

In some embodiments, the plasma print head assembly can be used in anyof the following possible combinations, for printing single or multilayered optical materials: aerosol jet printing of one layer and plasmajet printing of subsequent layers or vice-versa; plasma jet printing ofone or more than one layer; plasma treatment of the surface before,during and after printing for any of the reasons including activation,adhesion, printing, polymerization or etching or curing of opticalmaterials.

In some embodiments, the plasma jet print head can be used to printmaterials with controlled optical properties including refractive index,dielectric strength, optical and photonics transparency, plasmonicproperties, or a combination thereof.

Described herein is an apparatus for printing one or more opticalmaterials with tunable refractive index, tunable photonic transparencyusing in-situ plasma processing by introduction of various gas mixturesand aerosolized liquid precursor to print dielectric coating and dopeddielectric coating with tailored refractive index, graded refractiveindex, transparency, extinction coefficient, or a combination thereof.

In some embodiments, the plasma induced refractive index change canhappen by any one or a combination of plasma treatment of surface,during printing by in situ plasma process through gas and precursormixtures; plasma-based doping of materials; post-plasma treatment ofprinted surface, wherein, the plasma is generated using the said printhead using atmospheric pressure process.

In some embodiments, the apparatus for printing optical materials withdefined refractive index and pattern allows a combination of featuresincluding aerosol jet printing, plasma jet printing, plasma treatment,or a combination thereof.

In some embodiments, the apparatus is for printing plasmonic materialswith tunable metal particle density, film thickness, opticaltransparency, or a combination thereof, using in situ plasma processingby introduction of various gas mixtures and aerosolized metal colloid toprint plasmonic coating. In some cases, the said plasmonic materials canbe gold, silver, aluminum, magnesium, graphene, lead suphide, quantumdots, or a combination thereof. In some cases, the printed plasmonicmaterials can be used for selective filtering of color for displays,and/or coupling of photons for plasmonic optical devices and hybridphotonics devices.

In some embodiments, an apparatus is for printing polymer resins withoutdepositing the solvents in the film and by eliminating additionalprocess steps like thermal treatment, curing required to remove thesolvents and to cure the resin wherein the film thickness can beprecisely controlled without depending on the solvent removal, curingetc., and by avoiding air bubble formation in the film.

In some embodiments, both polymeric optical materials and plasmonicmaterials can either be introduced simultaneously to the primarydielectric through the inlet to create a hybrid coating or introducedone after the other to get a layered coating.

In some embodiments, the primary dielectric tube could be made of anydielectric material not limited to ceramic, inorganic materials,including alumina, quartz, teflon, silica, Macor, aluminum oxide, or acombination thereof.

Described herein are methods for direct write dry printing of opticaland plasmonic materials using atmospheric pressure plasma jet, in whichthe material properties that are tuned using gaseous plasma and amixture of precursors and gas mixtures in the plasma print head, tofabricate photonics and hybrid electronic photonic devices

In some embodiments, the plasma jet apparatus comprises a plasma printhead, wherein the plasma print head comprises: a dielectric tube whoseone end is connected directly to an atomizer or nebulizer placed inclose proximity through an inlet manifold and the second end connectedto a nozzle, wherein, two or more electrodes disposed over the outerside of the dielectric and connected to a shielded high voltage cableand power supply to generate plasma discharge inside the primarydielectric tube; a nebulizer connected to one or more than on liquidprecursor source containing the polymeric and or plasmonic opticalmaterials to be printed, attached directly to the print head using aninlet manifold connecting one end of the primary dielectric tube; aremovable, replaceable and independently movable mask connected to apiezo motor placed at the outlet of the nozzle such that the materialscoming out of the dielectric tube is focused by the mask to thesubstrate; an enclosure containing a temperature sensor for measuringthe temperature of the primary dielectric tube for in-situ monitoringand optimization of the plasma, an electromagnetic interferenceshielding mesh to prevent electromagnetic interference from the plasmaprint head to adjacent electronics, provision to place other sensors inclose proximity to dielectric tube, wherein the enclosure encloses thedielectric tube, electrodes and high voltage cables, piezo motor withmask, inlet manifold, nebulizer for generating aerosol mist; multiplefluid connection to the print head to introduce materials with similaror varying optical properties and gas into the print head.

The ability to articulate the print head relative to the workpiece(substrate) combined with the ability to modify the size and shape ofthe print head orifice provides an exceptional level of control over thegeometry and cross sectional thickness of the printed material.

The ability to change the direction of the print media such as plasma,gas and material used to print, exiting the print head by substitutingthe nozzle assembly with a nozzle assembly that has a defined orchangeable curvature such that the direction of the print mediamaterials (plasma, gas and material used to print) exiting the printhead may be changed relative to the orientation of the print head suchthat printing may be performed within complex structures that the printhead assembly would not be able to access.

In some embodiments, the one or more liquid precursor source containingthe monomer or polymer or plasmonic optical materials to be printed arepassed through the atomizer or nebulizer present in the print head thatgenerates an aerosol and the aerosol introduced into the plasma zone ofthe print head along with gas mixtures;

In some embodiments, the volume and the diameter of the aerosolizedliquid droplets are controlled by atomizer, wherein the liquid precursorcan be a precursor or monomer or polymer or colloid or ink.

In some embodiments, the aerosol mist can be generated by a pneumatic orpiezo electric nebulizer. The right nebulizer is chosen depending on therequired aerosol droplet size, nature and viscosity of liquids. In somecases, when the atomizer is a piezo electric nebulizer, the operatingfrequency can be independently controlled such that the droplet size andvolume of the aerosol carrying optical materials is optimized for plasmajet printing

In some embodiments, the aerosol mist can be generated by a pneumatic orpiezo electric nebulizer. The right nebulizer is chosen depending on therequired aerosol droplet size, nature and viscosity of liquids. In somecases, when the atomizer is a piezo electric nebulizer, the operatingfrequency can be independently controlled such that the droplet size andvolume of the aerosol carrying optical materials is optimized for plasmajet printing

In some embodiments, the plasma jet print head can be used for surfacetreatments like for example pre-treatment of the surface usingatmospheric plasma to create hydrophobic and/or hydrophilic surfaces, orfor post treatment using atmospheric plasma with selective gas ratios toetch or cure or act as a UV source or to create morphology change on thesurface.

In some embodiments, the mask attached to the plasma jet print headdevice may be moved independent of the print head. In some cases, themask attached to the plasma jet print head device may be moved incombination with the print head using a piezo motor to draw one or morepatterns of materials on to the substrate either by printing, plasmaetching, plasma curing, or a combination thereof, of materials.

In some embodiments, the plasma print head assembly can be used in anyof the possible combinations, for printing single or multi layeredoptical materials: aerosol jet printing of one layer and plasma jetprinting of subsequent layers or vice-versa; plasma jet printing of oneor more than one layer; plasma treatment of the surface before, duringand after printing for any of the reasons including activation,adhesion, printing, polymerization or etching or curing of opticalmaterials.

Described herein is a method for manufacturing active polymer photonicdevices comprising: printing a first cladding layer on the substrateusing plasma jet print head; imprinting the first cladding layer;printing a core layer on the imprinted first cladding layer using plasmajet print head and printing a second cladding layer on the core layerusing the plasma jet print head, plasma jet printing of an electrode onthe cladding layer, wherein, the plasma can be used to pre-treat, printand post treat the surface and the materials printed to achieve any ofthe following including activation, adhesion, printing, curing, UVsource, etching, polymerization, doping, tuning of optical propertiesincluding refractive index etc.

Described herein is a method for manufacturing optical waveguidescomprising: printing a first cladding layer on the substrate usingplasma jet print head, imprinting the first cladding layer; printing acore layer on the imprinted first cladding layer using plasma jet printhead and printing a second cladding layer on the core layer using theplasma jet print head wherein, the plasma can be used to pre-treat,print and post treat the surface and the materials printed to achieveany of the following including activation, adhesion, printing, curing,UV source, etching, polymerization, doping, tuning of optical propertiesincluding refractive index etc. In some cases, the plasma jet printingcan be used for selectively coating any one or more layers of theoptical waveguides.

Described herein is a method for manufacturing optical waveguidescomprising: printing a first cladding layer on the substrate usingplasma jet print head; imprinting the first cladding layer; printing acore layer on the imprinted first cladding layer using plasma jet printhead, printing a second cladding layer on the core layer using theplasma jet print head; printing an electrode connected either to thefirst cladding layer or to second cladding layer or to both the claddinglayers; wherein, the plasma can be used to pre-treat, print andpost-treat the surface and the materials printed to achieve any of thefollowing including activation, adhesion, printing, curing, UV source,etching, polymerization, doping, tuning of optical properties includingrefractive index etc., wherein, the plasma jet printing can be used forselectively coating any one or more than one layers of the opticalwaveguides and also the electrically conducting electrodes.

In some cases, the material used for printing cladding and core are madeof liquid polymers or organo silane or siloxanes, wherein said opticalelement forming material is selected from the polymer liquid groupconsisting of UV-curable adhesives, UV-curable resins, glasses,amorphous polytetrafluoroethylene, translucent polymers, solvenatedpolymers, PMMA, poly styrene, polyimide, tetra ethyl oath silicate,hexamethyl disiloxane, hexamethyldisilazane, polymers containing laserdyes, sol-gel materials, optical waxes, optical epoxies, opticalpolymers, silicon dioxide, polyimide, polynorbornenes, benzocyclobutene,and PTFE and by using silicon based polymeric dielectric hydrogensilsesquioxane (HSQ) and methylsilsesquioxane (MSQ).

In some cases, the refractive index of core material is higher than therefractive index of the cladding. In some cases, the optical materialsand photonics devices are cladded multimode waveguides and wherein theoptical materials having a first index of refraction are printed fromsaid printing device to said substrate and second optical materialforming a core with a second index of refraction which is higher thanthe cladding are printed from said plasma jet printing device to saidsubstrate

In some cases, the polymer-based waveguide device as described hereincomprises a substrate is made of a material selected from a groupcomprising silicon single crystal, silicon polycrystal, lithium niobatesingle crystal, quartz, optical glass and optical plastic. Opticalpolymers can generally be grouped into classes such as thermoplastics,thermosets or photopolymers, to name a few.

In some embodiments, the silicon dioxide dielectric strength (K) can bechanged by introducing carbon- or fluorine-based source for printingsilicon dioxide with low K and introducing nitrogen for high Kdielectric film by controlling the plasma process parameters; printingof low K dielectric can be achieved by using polymers includingpolyimide, polynorbornenes, benzocyclobutene, and PTFE and by usingsilicon based polymeric dielectric hydrogen silsesquioxane (HSQ) andmethylsilsesquioxane (MSQ); printing of high K dielectric can beachieved by using oxynitride and by introducing nitrogen in the silicondi oxide.

In some cases, a silicon dioxide coating can be doped using B, P, Al,Ga, As, Sb or combinations thereof using plasma process parameters.

In some cases, the precursor and gas flow rates individually can be from5 standard cubic centimeter per minute (SCCM) to 5,000 sccm. In somecases, the power used to generate the plasma can vary from 1 Watts to100 Watts. In some cases, the power supply used for generating theplasma discharge comprises any one or a combination of DC, pulsed DC,AC, microwave and RF. In some cases, the working distance between theplasma print head and the substrate can vary from 1 millimeter to 5centimeters.

In some cases, the primary gas used to generate plasma discharge can befrom any of the gases comprising inert gases, helium, argon, nitrogen,hydrogen, oxygen, sulphur hexafluoride, air, mixture of inert andreactive gases.

In some cases, the thickness of the film that can be printed usingplasma jet printing can vary from 1 nm to 1 centimeter or more dependingon the need.

In some cases, the printing resolution or the line width can vary from100 nanometers to 5 centimeters. For large area coating, the print headcan be rastered.

In some embodiments, the waveguide is made up only of an optical core.In other embodiments, the waveguide is made up of an optical core, andone or more optical cladding layers

In one embodiment, the refractive index of the bottom cladding layer issubstantially equal to the refractive index of the top cladding layer.

The core material in the core region may be in the solid phase or thegas phase. For example, the core material may be a solid polymer such aspolyethylene, polypropylene, polytetrafluoroethylene (PTFE), or thelike. Alternatively, the core material may be one or more gases, such asair. Air has a low dielectric strength of approximately 1.0.

One or more patterns can be printed on a substrate. The one or morepatterns can be a single layer or can be multilayered. The pattern canbe directly printed on the devices or attached to other devices (opticalor non-optical), or elements of devices (e.g., electrodes).

In some embodiments, the materials that can be printed includes twodimensional materials such as graphene, silicone, and germanene,dichalcogenides (MX2), hexagonal boron nitride (hBN), phosphorene,silicene, oxides, graphene oxide and reduced graphene oxide multilayers.

In some cases, the material used for printing electrodes is at least oneof, a metal, a conductive polymer, organic electronic materials, aconductive metal oxide, carbon nanotubes, and graphene.

In some cases, the material used for printing electrodes can be acolloid containing metal or metal oxide and the plasma jet printingprocess can be used to tailor the oxidation state and electronicstructure of the metal or metal oxide to print a high quality conductingelectrode on the said surface. Metals such as gold, silver, platinum,copper, and alloys, and conductive materials such carbon black,conductive epoxy, or indium-tin-oxide (ITO), can also be used.

In some cases, the plasmonic materials can be any of the following:gold, silver, aluminum, magnesium, graphene, metamaterials, quantumdots, lead sulphide, or a combination thereof.

In some cases, the printed plasmonic structures absorb specificwavelengths depending its density of packing, film thickness, nature ofmaterial and on a nearby refractive index, all of which can becontrolled by plasma process parameters.

In some cases, the printed plasmonic materials can be used to createlocalized surface plasmon polarity and surface plasmon resonance. Insome cases, the printed plasmonic materials can be used for couplingphotonics and plasmon waveguides, color change application, displays,optical packaging etc.

Another aspect of the invention is a fluid delivery assembly forintroducing aerosols into the print head for plasma jet printing.

In some cases, to print materials using a plasma jet printer, the one ormore materials to be printed are aerosolized and introduced into theplasma jet print head. In some embodiments, the one or more aerosolizedmaterials interact with plasma within the plasma jet print. Afterinteracting with the plasma, the one or more aerosolized materials aredirected towards the one or more substrates to be printed.

In order to increase the efficiency and reliability of printing, severalcharacteristics of the aerosolized particles may need to be controlledefficiently. In some cases, the characteristics of the aerosolizedparticles to be controlled may include the density, the flow rate, thedroplet size, the atomization rate, the size distribution, or acombination thereof.

To aerosolize the one or more materials, one or more atomizers can beplaced close to the plasma jet print head using a modular fluid deliveryassembly. In some cases, the modular fluid assembly can be attached tothe plasma jet print head. In some cases, the modular fluid assembly canbe detached to the plasma jet print head.

There are at least two major issues in aerosol assisted plasma jetprinting when the atomizer is placed close to the print head: (1) theelectrical arcing between the electrodes in the plasma jet print headused to generate the plasma and the metallic component of the atomizerplaced near the electrode. This electrical arcing will damage theatomizer and also not result in stable plasma in print head. This willresult in no or very poor printing; and (2) a gas supply introduced tocarry the aerosol and generate the plasma having a direct impact on theaerosol and completely displacing the aerosol towards the wall, when thegas flow comes in direct contact with the aerosol, resulting in loss ofaerosolized materials to the wall of the assembly. When this happens,there will not be any printing as the materials will be lost to innersurface of the dielectric tube or spacer.

Described herein is a modular fluid delivery assembly is designed forefficient delivery of aerosolized ink to a plasma jet print headdescribed herein for plasma jet printing. The modular fluid deliveryassembly is designed in such a way to avoid arcing between the metallicatomizer and the electrode of the print head. In addition, the fluiddelivery assembly provided herein efficiently carries the aerosolizedmaterial, the aerosol, to the print head without the aerosol gettingdisplaced towards the wall and without the mist of the aerosol gettingquenched.

In some embodiments, the fluid delivery assembly comprises of an inkreservoir. In some embodiments, the volume of the ink reservoir is about100 cubic mm to about 10,000 cubic mm. In some embodiments, the volumeof the ink reservoir is at least about 100 cubic mm. In someembodiments, the volume of the ink reservoir is at most about 10,000cubic mm. In some embodiments, the volume of the ink reservoir is about100 cubic mm to about 500 cubic mm, about 100 cubic mm to about 1,000cubic mm, about 100 cubic mm to about 2,000 cubic mm, about 100 cubic mmto about 3,000 cubic mm, about 100 cubic mm to about 4,000 cubic mm,about 100 cubic mm to about 5,000 cubic mm, about 100 cubic mm to about6,000 cubic mm, about 100 cubic mm to about 7,000 cubic mm, about 100cubic mm to about 8,000 cubic mm, about 100 cubic mm to about 9,000cubic mm, about 100 cubic mm to about 10,000 cubic mm, about 500 cubicmm to about 1,000 cubic mm, about 500 cubic mm to about 2,000 cubic mm,about 500 cubic mm to about 3,000 cubic mm, about 500 cubic mm to about4,000 cubic mm, about 500 cubic mm to about 5,000 cubic mm, about 500cubic mm to about 6,000 cubic mm, about 500 cubic mm to about 7,000cubic mm, about 500 cubic mm to about 8,000 cubic mm, about 500 cubic mmto about 9,000 cubic mm, about 500 cubic mm to about 10,000 cubic mm,about 1,000 cubic mm to about 2,000 cubic mm, about 1,000 cubic mm toabout 3,000 cubic mm, about 1,000 cubic mm to about 4,000 cubic mm,about 1,000 cubic mm to about 5,000 cubic mm, about 1,000 cubic mm toabout 6,000 cubic mm, about 1,000 cubic mm to about 7,000 cubic mm,about 1,000 cubic mm to about 8,000 cubic mm, about 1,000 cubic mm toabout 9,000 cubic mm, about 1,000 cubic mm to about 10,000 cubic mm,about 2,000 cubic mm to about 3,000 cubic mm, about 2,000 cubic mm toabout 4,000 cubic mm, about 2,000 cubic mm to about 5,000 cubic mm,about 2,000 cubic mm to about 6,000 cubic mm, about 2,000 cubic mm toabout 7,000 cubic mm, about 2,000 cubic mm to about 8,000 cubic mm,about 2,000 cubic mm to about 9,000 cubic mm, about 2,000 cubic mm toabout 10,000 cubic mm, about 3,000 cubic mm to about 4,000 cubic mm,about 3,000 cubic mm to about 5,000 cubic mm, about 3,000 cubic mm toabout 6,000 cubic mm, about 3,000 cubic mm to about 7,000 cubic mm,about 3,000 cubic mm to about 8,000 cubic mm, about 3,000 cubic mm toabout 9,000 cubic mm, about 3,000 cubic mm to about 10,000 cubic mm,about 4,000 cubic mm to about 5,000 cubic mm, about 4,000 cubic mm toabout 6,000 cubic mm, about 4,000 cubic mm to about 7,000 cubic mm,about 4,000 cubic mm to about 8,000 cubic mm, about 4,000 cubic mm toabout 9,000 cubic mm, about 4,000 cubic mm to about 10,000 cubic mm,about 5,000 cubic mm to about 6,000 cubic mm, about 5,000 cubic mm toabout 7,000 cubic mm, about 5,000 cubic mm to about 8,000 cubic mm,about 5,000 cubic mm to about 9,000 cubic mm, about 5,000 cubic mm toabout 10,000 cubic mm, about 6,000 cubic mm to about 7,000 cubic mm,about 6,000 cubic mm to about 8,000 cubic mm, about 6,000 cubic mm toabout 9,000 cubic mm, about 6,000 cubic mm to about 10,000 cubic mm,about 7,000 cubic mm to about 8,000 cubic mm, about 7,000 cubic mm toabout 9,000 cubic mm, about 7,000 cubic mm to about 10,000 cubic mm,about 8,000 cubic mm to about 9,000 cubic mm, about 8,000 cubic mm toabout 10,000 cubic mm, or about 9,000 cubic mm to about 10,000 cubic mm.In some embodiments, the volume of the ink reservoir is about 100 cubicmm, about 500 cubic mm, about 1,000 cubic mm, about 2,000 cubic mm,about 3,000 cubic mm, about 4,000 cubic mm, about 5,000 cubic mm, about6,000 cubic mm, about 7,000 cubic mm, about 8,000 cubic mm, about 9,000cubic mm, or about 10,000 cubic mm.

In some embodiments, the fluid delivery assembly further comprises anatomizer, one or more fluid inlets, a gas inlet, a lip and a dielectricspacer.

In some cases, the atomizer comprises a piezoelectric vibrator, atransducer, or a combination. The atomizer can generate an aerosol whena liquid comes in direct contact with the atomizer.

In some cases, a perforated plate is placed inside the ink reservoir.The perforated plate can allow the aerosol to exit towards the printhead on the other side of the ink reservoir.

In some embodiments, the fluid delivery assembly can be a stand-alonemodule with pre-filled ink cartridge. In those cases, the fluid deliveryassembly and/or the cartridge case can be replaced once the ink isfinished.

In some embodiments, the fluid delivery assembly can also be used forcontinuous feeding of ink into ink reservoir and to the print headthrough a liquid inlet and outlet on top of the reservoir. The liquidinlet and outlet helps re-circulate the ink while the atomizer at thebottom of the reservoir continuously aerosolizes the ink. The aerosol isthen directed to the plasma jet print head using a gas inlet placedbelow the atomizer and at the side of the assembly.

In some cases, the gas inlet is located at the bottom of the atomizerand to the side, so that the gas can carry the aerosol to the printhead. To generate plasma, the gas flow rate can vary from 50 sccm to5000 sccm. In some embodiments, the gas flow rate is about 50 sccm toabout 5,000 sccm. In some embodiments, the gas flow rate is at leastabout 50 sccm. In some embodiments, the gas flow rate is at most about5,000 sccm. In some embodiments, the gas flow rate is about 50 sccm toabout 100 sccm, about 50 sccm to about 250 sccm, about 50 sccm to about500 sccm, about 50 sccm to about 750 sccm, about 50 sccm to about 1,000sccm, about 50 sccm to about 1,500 sccm, about 50 sccm to about 2,000sccm, about 50 sccm to about 2,500 sccm, about 50 sccm to about 3,000sccm, about 50 sccm to about 4,000 sccm, about 50 sccm to about 5,000sccm, about 100 sccm to about 250 sccm, about 100 sccm to about 500sccm, about 100 sccm to about 750 sccm, about 100 sccm to about 1,000sccm, about 100 sccm to about 1,500 sccm, about 100 sccm to about 2,000sccm, about 100 sccm to about 2,500 sccm, about 100 sccm to about 3,000sccm, about 100 sccm to about 4,000 sccm, about 100 sccm to about 5,000sccm, about 250 sccm to about 500 sccm, about 250 sccm to about 750sccm, about 250 sccm to about 1,000 sccm, about 250 sccm to about 1,500sccm, about 250 sccm to about 2,000 sccm, about 250 sccm to about 2,500sccm, about 250 sccm to about 3,000 sccm, about 250 sccm to about 4,000sccm, about 250 sccm to about 5,000 sccm, about 500 sccm to about 750sccm, about 500 sccm to about 1,000 sccm, about 500 sccm to about 1,500sccm, about 500 sccm to about 2,000 sccm, about 500 sccm to about 2,500sccm, about 500 sccm to about 3,000 sccm, about 500 sccm to about 4,000sccm, about 500 sccm to about 5,000 sccm, about 750 sccm to about 1,000sccm, about 750 sccm to about 1,500 sccm, about 750 sccm to about 2,000sccm, about 750 sccm to about 2,500 sccm, about 750 sccm to about 3,000sccm, about 750 sccm to about 4,000 sccm, about 750 sccm to about 5,000sccm, about 1,000 sccm to about 1,500 sccm, about 1,000 sccm to about2,000 sccm, about 1,000 sccm to about 2,500 sccm, about 1,000 sccm toabout 3,000 sccm, about 1,000 sccm to about 4,000 sccm, about 1,000 sccmto about 5,000 sccm, about 1,500 sccm to about 2,000 sccm, about 1,500sccm to about 2,500 sccm, about 1,500 sccm to about 3,000 sccm, about1,500 sccm to about 4,000 sccm, about 1,500 sccm to about 5,000 sccm,about 2,000 sccm to about 2,500 sccm, about 2,000 sccm to about 3,000sccm, about 2,000 sccm to about 4,000 sccm, about 2,000 sccm to about5,000 sccm, about 2,500 sccm to about 3,000 sccm, about 2,500 sccm toabout 4,000 sccm, about 2,500 sccm to about 5,000 sccm, about 3,000 sccmto about 4,000 sccm, about 3,000 sccm to about 5,000 sccm, or about4,000 sccm to about 5,000 sccm. In some embodiments, the gas flow rateis about 50 sccm, about 100 sccm, about 250 sccm, about 500 sccm, about750 sccm, about 1,000 sccm, about 1,500 sccm, about 2,000 sccm, about2,500 sccm, about 3,000 sccm, about 4,000 sccm, or about 5,000 sccm.

In some cases, when the gas is introduced with such flow rate directlyfrom the side, facing the rear side of the atomizer through which theaerosol exits, the aerosol gets displaced by the gas flow towards thewall and the aerosol gets quenched. In order to avoid direct exposure ofthe gas to the aerosol mist exiting the atomizer, a lip is built at thebottom of the atomizer to prevent direct contact of the gas flow withthe aerosol exiting the atomizer. The aerosol is then carried by the gastowards the plasma jet printer, where the materials in the aerosol areaccelerated by the plasma towards the substrate. The lip ensures thatthe gas flow pressure is not directly exerted on to the aerosol exitingthe atomizer.

In some embodiments, the length of the lip is about 2 mm to about 100mm. In some embodiments, the length of the lip is at least about 2 mm.In some embodiments, the length of the lip is at most about 100 mm. Insome embodiments, the length of the lip is about 2 mm to about 5 mm,about 2 mm to about 10 mm, about 2 mm to about 20 mm, about 2 mm toabout 30 mm, about 2 mm to about 40 mm, about 2 mm to about 50 mm, about2 mm to about 60 mm, about 2 mm to about 70 mm, about 2 mm to about 80mm, about 2 mm to about 90 mm, about 2 mm to about 100 mm, about 5 mm toabout 10 mm, about 5 mm to about 20 mm, about 5 mm to about 30 mm, about5 mm to about 40 mm, about 5 mm to about 50 mm, about 5 mm to about 60mm, about 5 mm to about 70 mm, about 5 mm to about 80 mm, about 5 mm toabout 90 mm, about 5 mm to about 100 mm, about 10 mm to about 20 mm,about 10 mm to about 30 mm, about 10 mm to about 40 mm, about 10 mm toabout 50 mm, about 10 mm to about 60 mm, about 10 mm to about 70 mm,about 10 mm to about 80 mm, about 10 mm to about 90 mm, about 10 mm toabout 100 mm, about 20 mm to about 30 mm, about 20 mm to about 40 mm,about 20 mm to about 50 mm, about 20 mm to about 60 mm, about 20 mm toabout 70 mm, about 20 mm to about 80 mm, about 20 mm to about 90 mm,about 20 mm to about 100 mm, about 30 mm to about 40 mm, about 30 mm toabout 50 mm, about 30 mm to about 60 mm, about 30 mm to about 70 mm,about 30 mm to about 80 mm, about 30 mm to about 90 mm, about 30 mm toabout 100 mm, about 40 mm to about 50 mm, about 40 mm to about 60 mm,about 40 mm to about 70 mm, about 40 mm to about 80 mm, about 40 mm toabout 90 mm, about 40 mm to about 100 mm, about 50 mm to about 60 mm,about 50 mm to about 70 mm, about 50 mm to about 80 mm, about 50 mm toabout 90 mm, about 50 mm to about 100 mm, about 60 mm to about 70 mm,about 60 mm to about 80 mm, about 60 mm to about 90 mm, about 60 mm toabout 100 mm, about 70 mm to about 80 mm, about 70 mm to about 90 mm,about 70 mm to about 100 mm, about 80 mm to about 90 mm, about 80 mm toabout 100 mm, or about 90 mm to about 100 mm. In some embodiments, thelength of the lip is about 2 mm, about 5 mm, about 10 mm, about 20 mm,about 30 mm, about 40 mm, about 50 mm, about 60 mm, about 70 mm, about80 mm, about 90 mm, or about 100 mm.

The assembly is designed in such a way that the metallic component ofthe atomizer including the drilled or perforated plate, and thetransducer and/or piezo electric vibrator, is separated from the topelectrode of the plasma jet print head by a minimum of 1.2 times theseparation distance between the electrodes of the plasma manifold inplasma jet print head.

This separation ensures that there is no arcing between the atomizer andthe top electrode of the print head during plasma jet printing. In orderto facilitate the separation between the atomizer and the top electrodeof the print head, a dielectric spacer may be used to connect theatomizer and the print head. The dielectric spacer is designed in such away that the inner wall of the dielectric is smooth to avoid the aerosolfrom getting adsorbed on the inner surface and to help transport theaerosol mist and the gas to the print head. The dielectric spacer can beplaced below the lip of the atomizer assembly and close to the gas inletsuch that the gas inlet is not blocked by the dielectric spacer. Thedielectric spacer can also be used as an inner dielectric tube whoselength and shape can be varied such that the tube ends before meetingthe electrodes or in between the electrodes or extended beyond theelectrodes.

In some embodiments, the diameter of the dielectric spacer is about 1 mmto about 40 mm. In some embodiments, the diameter of the dielectricspacer is at least about 1 mm. In some embodiments, the diameter of thedielectric spacer is at most about 40 mm. In some embodiments, thediameter of the dielectric spacer is about 1 mm to about 5 mm, about 1mm to about 10 mm, about 1 mm to about 15 mm, about 1 mm to about 20 mm,about 1 mm to about 25 mm, about 1 mm to about 30 mm, about 1 mm toabout 35 mm, about 1 mm to about 40 mm, about 5 mm to about 10 mm, about5 mm to about 15 mm, about 5 mm to about 20 mm, about 5 mm to about 25mm, about 5 mm to about 30 mm, about 5 mm to about 35 mm, about 5 mm toabout 40 mm, about 10 mm to about 15 mm, about 10 mm to about 20 mm,about 10 mm to about 25 mm, about 10 mm to about 30 mm, about 10 mm toabout 35 mm, about 10 mm to about 40 mm, about 15 mm to about 20 mm,about 15 mm to about 25 mm, about 15 mm to about 30 mm, about 15 mm toabout 35 mm, about 15 mm to about 40 mm, about 20 mm to about 25 mm,about 20 mm to about 30 mm, about 20 mm to about 35 mm, about 20 mm toabout 40 mm, about 25 mm to about 30 mm, about 25 mm to about 35 mm,about 25 mm to about 40 mm, about 30 mm to about 35 mm, about 30 mm toabout 40 mm, or about 35 mm to about 40 mm. In some embodiments, thediameter of the dielectric spacer is about 1 mm, about 5 mm, about 10mm, about 15 mm, about 20 mm, about 25 mm, about 30 mm, about 35 mm, orabout 40 mm.

In some embodiments, the length of the dielectric spacer is about 5 mmto about 120 mm. In some embodiments, the length of the dielectricspacer is at least about 5 mm. In some embodiments, the length of thedielectric spacer is at most about 120 mm. In some embodiments, thelength of the dielectric spacer is about 5 mm to about 10 mm, about 5 mmto about 20 mm, about 5 mm to about 30 mm, about 5 mm to about 40 mm,about 5 mm to about 50 mm, about 5 mm to about 60 mm, about 5 mm toabout 70 mm, about 5 mm to about 80 mm, about 5 mm to about 90 mm, about5 mm to about 100 mm, about 5 mm to about 120 mm, about 10 mm to about20 mm, about 10 mm to about 30 mm, about 10 mm to about 40 mm, about 10mm to about 50 mm, about 10 mm to about 60 mm, about 10 mm to about 70mm, about 10 mm to about 80 mm, about 10 mm to about 90 mm, about 10 mmto about 100 mm, about 10 mm to about 120 mm, about 20 mm to about 30mm, about 20 mm to about 40 mm, about 20 mm to about 50 mm, about 20 mmto about 60 mm, about 20 mm to about 70 mm, about 20 mm to about 80 mm,about 20 mm to about 90 mm, about 20 mm to about 100 mm, about 20 mm toabout 120 mm, about 30 mm to about 40 mm, about 30 mm to about 50 mm,about 30 mm to about 60 mm, about 30 mm to about 70 mm, about 30 mm toabout 80 mm, about 30 mm to about 90 mm, about 30 mm to about 100 mm,about 30 mm to about 120 mm, about 40 mm to about 50 mm, about 40 mm toabout 60 mm, about 40 mm to about 70 mm, about 40 mm to about 80 mm,about 40 mm to about 90 mm, about 40 mm to about 100 mm, about 40 mm toabout 120 mm, about 50 mm to about 60 mm, about 50 mm to about 70 mm,about 50 mm to about 80 mm, about 50 mm to about 90 mm, about 50 mm toabout 100 mm, about 50 mm to about 120 mm, about 60 mm to about 70 mm,about 60 mm to about 80 mm, about 60 mm to about 90 mm, about 60 mm toabout 100 mm, about 60 mm to about 120 mm, about 70 mm to about 80 mm,about 70 mm to about 90 mm, about 70 mm to about 100 mm, about 70 mm toabout 120 mm, about 80 mm to about 90 mm, about 80 mm to about 100 mm,about 80 mm to about 120 mm, about 90 mm to about 100 mm, about 90 mm toabout 120 mm, or about 100 mm to about 120 mm. In some embodiments, thelength of the dielectric spacer is about 5 mm, about 10 mm, about 20 mm,about 30 mm, about 40 mm, about 50 mm, about 60 mm, about 70 mm, about80 mm, about 90 mm, about 100 mm, or about 120 mm.

The atomizer assembly design can also be changed so that the atomizer isplaced at the side of the assembly and the gas introduced from the top.Also more than one atomizers and reservoir unit combinations can beattached to the atomizer assembly and connected on the top side of thedielectric spacer. The gas inlet can be introduced from top and morethan one atomizer and reservoir units connected at the side of theassembly can introduce multiple materials from the inks/aerosols intothe inner portion of the assembly and all the aerosols from multiplereservoirs/atomizers carried into the plasma jet print head through thedielectric spacer. This will allow multi-materials and hybrid coatingsto be printed. The composition of the printed material can be preciselycontrolled by individually controlling the fluid delivery from eachatomizer/reservoir combination.

The atomizer assembly comprises a dielectric material to avoid plasmaarcing between atomizer and electrode. An operating frequency range ofthe atomizer can vary to create aerosols comprising different materials.The aerosols can comprise droplets of various sizes. The aerosols to beprinted and atomizers with different frequency ranges can be used toaerosolize and deliver appropriate quantity and droplet size of theaerosol to the plasma region of the print head. Atomizers of varioustypes including mesh nebulizer, ultrasonic nebulizer, or a combinationthereof can be used.

In some embodiments, the operating frequency is about 0.05 MHz to about10 MHz. In some embodiments, the operating frequency is at least about0.05 MHz. In some embodiments, the operating frequency is at most about10 MHz. In some embodiments, the operating frequency is about 0.05 MHzto about 0.5 MHz, about 0.05 MHz to about 1 MHz, about 0.05 MHz to about2 MHz, about 0.05 MHz to about 3 MHz, about 0.05 MHz to about 4 MHz,about 0.05 MHz to about 5 MHz, about 0.05 MHz to about 6 MHz, about 0.05MHz to about 7 MHz, about 0.05 MHz to about 8 MHz, about 0.05 MHz toabout 9 MHz, about 0.05 MHz to about 10 MHz, about 0.5 MHz to about 1MHz, about 0.5 MHz to about 2 MHz, about 0.5 MHz to about 3 MHz, about0.5 MHz to about 4 MHz, about 0.5 MHz to about 5 MHz, about 0.5 MHz toabout 6 MHz, about 0.5 MHz to about 7 MHz, about 0.5 MHz to about 8 MHz,about 0.5 MHz to about 9 MHz, about 0.5 MHz to about 10 MHz, about 1 MHzto about 2 MHz, about 1 MHz to about 3 MHz, about 1 MHz to about 4 MHz,about 1 MHz to about 5 MHz, about 1 MHz to about 6 MHz, about 1 MHz toabout 7 MHz, about 1 MHz to about 8 MHz, about 1 MHz to about 9 MHz,about 1 MHz to about 10 MHz, about 2 MHz to about 3 MHz, about 2 MHz toabout 4 MHz, about 2 MHz to about 5 MHz, about 2 MHz to about 6 MHz,about 2 MHz to about 7 MHz, about 2 MHz to about 8 MHz, about 2 MHz toabout 9 MHz, about 2 MHz to about 10 MHz, about 3 MHz to about 4 MHz,about 3 MHz to about 5 MHz, about 3 MHz to about 6 MHz, about 3 MHz toabout 7 MHz, about 3 MHz to about 8 MHz, about 3 MHz to about 9 MHz,about 3 MHz to about 10 MHz, about 4 MHz to about 5 MHz, about 4 MHz toabout 6 MHz, about 4 MHz to about 7 MHz, about 4 MHz to about 8 MHz,about 4 MHz to about 9 MHz, about 4 MHz to about 10 MHz, about 5 MHz toabout 6 MHz, about 5 MHz to about 7 MHz, about 5 MHz to about 8 MHz,about 5 MHz to about 9 MHz, about 5 MHz to about 10 MHz, about 6 MHz toabout 7 MHz, about 6 MHz to about 8 MHz, about 6 MHz to about 9 MHz,about 6 MHz to about 10 MHz, about 7 MHz to about 8 MHz, about 7 MHz toabout 9 MHz, about 7 MHz to about 10 MHz, about 8 MHz to about 9 MHz,about 8 MHz to about 10 MHz, or about 9 MHz to about 10 MHz. In someembodiments, the operating frequency is about 0.05 MHz, about 0.5 MHz,about 1 MHz, about 2 MHz, about 3 MHz, about 4 MHz, about 5 MHz, about 6MHz, about 7 MHz, about 8 MHz, about 9 MHz, or about 10 MHz.

The replaceable atomizer unit has provision for controlling the flowrate of aerosol in to the plasma jet print head without causingelectrical arc between the electrodes in the print head and theatomizer.

In some cases, the replaceable atomizer unit comprises a piezo electricatomizer or transducer. In some cases, the atomizer comprises aplurality of pores in a mesh whose frequency and pore size can becontrolled. Atomizers with varying vibrating frequency and pore sizescan be chosen for a range of fluids such as organic fluids,nano-colloids, metallic nano-colloids, inorganic nano-colloids. In somecases, an atomizer assembly can be created for each class of materialsand/or colloids with varying particle size.

The surface energy of the atomizer can be tuned with hydrophobic coatingto prevent clogging of the pores and settling of materials on theatomizer.

The fluid delivery assembly allows for the attachment of more than onecartridges; such a configuration can introduce two or more inks, liquidprecursors, chemical reagents, or a combination, into the print head inthe form of one or more aerosols.

The fluid delivery assembly described herein comprising two or morecartridges can enable multi-material printing, multi-layered printing,hybrid coating, polymerization, the introduction of two or more inks orchemical reagents into the print head, or a combination thereof.

FIG. 27 shows a modular design of plasma jet print head comprising afluid delivery assembly. In this exemplary embodiment, the fluiddelivery assembly 510 comprises a cartridge 500. In some embodiments,the cartridge 500 can be mounted on top of a coupler 508. In some cases,the coupler 508 is connected to a plasma manifold 200 of the plasma jetprint head.

In some embodiments, the cartridge 500 comprises of an ink reservoir 502with an inlet 503 and an outlet 504, as shown in FIG. 1. In some cases,the inlet 503 and the outlet 504 are connected to an external tank (notshown in FIG. 27). The external tank allocates ink supply from anexternal tank to the ink reservoir via the inlet and outlet. In somecases, the ink is recycled back to the tank from the reservoir.

In some embodiments, the inlet 503 and the outlet 504 of the cartridge500 can be sealed after the ink reservoir is completely filled. In thosecases, the cartridge 500 containing the atomizer can be used as areplaceable sealed cartridge.

In some embodiments, an atomizer 501 is located at the bottom of the inkreservoir. In some cases, the atomizer 501 comprises a piezoelectriccomponent, a transducer, a vibrating mesh, or a combination thereof. Theatomizer can be independently controlled, using a battery or anelectrical input. The atomizer is used to generate an aerosol of anyliquid that comes into contact with it.

In some embodiments, the characteristics of the atomizer can be varieddepending on the application. In some cases, the atomizer 501 comprisesa piezoelectric device that generates aerosol of the ink when it comesin contact with the piezo material.

In some cases, the atomizer 501 comprises a vibrating mesh with afrequency of about 0.05 MHz to about 10 MHz. In some cases, thefrequency is about 0.05 MHz to about 10 MHz. In some cases, thefrequency is at least about 0.05 MHz. In some cases, the frequency is atmost about 10 MHz. In some cases, the frequency is about 0.05 MHz toabout 0.1 MHz, about 0.05 MHz to about 0.5 MHz, about 0.05 MHz to about1 MHz, about 0.05 MHz to about 5 MHz, about 0.05 MHz to about 10 MHz,about 0.1 MHz to about 0.5 MHz, about 0.1 MHz to about 1 MHz, about 0.1MHz to about 5 MHz, about 0.1 MHz to about 10 MHz, about 0.5 MHz toabout 1 MHz, about 0.5 MHz to about 5 MHz, about 0.5 MHz to about 10MHz, about 1 MHz to about 5 MHz, about 1 MHz to about 10 MHz, or about 5MHz to about 10 MHz. In some cases, the frequency is about 0.05 MHz,about 0.1 MHz, about 0.5 MHz, about 1 MHz, about 5 MHz, or about 10 MHz.

In some embodiments, the atomizer 501 generates an aerosol mist with aplurality of droplets. In some embodiments, the size of the droplets inthe plurality of droplets is about 1 μm to about 20 μm. In someembodiments, the size of the droplets in the plurality of droplets is atleast about 1 μm. In some embodiments, the size of the droplets in theplurality of droplets is at most about 20 μm. In some embodiments, thesize of the droplets in the plurality of droplets is about 1 μm to about5 μm, about 1 μm to about 10 μm, about 1 μm to about 15 μm, about 1 μmto about 20 μm, about 5 μm to about 10 μm, about 5 μm to about 15 μm,about 5 μm to about 20 μm, about 10 μm to about 15 μm, about 10 μm toabout 20 μm, or about 15 μm to about 20 μm. In some embodiments, thesize of the droplets in the plurality of droplets is about 1 μm, about 5μm, about 10 μm, about 15 μm, or about 20 μm.

In some cases, the atomizer 501 is placed on a perforated plate. Theperforated plate allows the aerosol to exit on the other side of the inkreservoir. The hole diameter (not shown in figure) of the perforatedplate (not shown in figure) can be chosen depending on the nature andtype of ink and the particle size of the nano- and/or micron-sizedmaterials dispersed in the ink and also on the size of aerosol dropletrequired for plasma jet printing.

In some cases, the amplitude of vibration of the atomizer, theatomization rate of the atomizer, or both, can be independentlycontrolled using a voltage source. In some cases, the voltage source canbe controlled using software. By varying the amplitude of vibration, thenumber of aerosols generated per minute can be controlled and bychanging the frequency of vibration, the aerosol particle sizedistribution can be precisely controlled.

In some embodiments, the atomizer 501 can be removed and replaced. Thismodular design enables reuse of the fluid delivery assembly 510 andcartridge 500 with different types of atomizers. The different atomizersmay vary in frequency range, amplitude range, diameter of the hole, or acombination thereof.

In some embodiments, a gas inlet 505 is located below the atomizer meshto carry the aerosol to the print head for printing.

In some embodiments, the cartridge delivers aerosolized ink to theplasma jet print head. In some cases, a lip 506 is located at the bottomof the cartridge 500 below the atomizer 501. The lip 506 aids indownward flow of aerosolized ink into the plasma manifold of the printhead. The lip assists in the prevention of direct contact of theaerosolized ink with the gas flow from the gas inlet 505. When the gasflow is introduced directly without a loop, the gas flow will face theaerosol with a high flow rate that displaces the wall of the print head,and quenches the aerosol.

In some embodiments, the gas flow rate is about 50 sccm to about 5,000sccm. In some embodiments, the gas flow rate is at least about 50 sccm.In some embodiments, the gas flow rate is at most about 5,000 sccm. Insome embodiments, the gas flow rate is about 50 sccm to about 100 sccm,about 50 sccm to about 250 sccm, about 50 sccm to about 500 sccm, about50 sccm to about 1,000 sccm, about 50 sccm to about 2,000 sccm, about 50sccm to about 3,000 sccm, about 50 sccm to about 4,000 sccm, about 50sccm to about 5,000 sccm, about 100 sccm to about 250 sccm, about 100sccm to about 500 sccm, about 100 sccm to about 1,000 sccm, about 100sccm to about 2,000 sccm, about 100 sccm to about 3,000 sccm, about 100sccm to about 4,000 sccm, about 100 sccm to about 5,000 sccm, about 250sccm to about 500 sccm, about 250 sccm to about 1,000 sccm, about 250sccm to about 2,000 sccm, about 250 sccm to about 3,000 sccm, about 250sccm to about 4,000 sccm, about 250 sccm to about 5,000 sccm, about 500sccm to about 1,000 sccm, about 500 sccm to about 2,000 sccm, about 500sccm to about 3,000 sccm, about 500 sccm to about 4,000 sccm, about 500sccm to about 5,000 sccm, about 1,000 sccm to about 2,000 sccm, about1,000 sccm to about 3,000 sccm, about 1,000 sccm to about 4,000 sccm,about 1,000 sccm to about 5,000 sccm, about 2,000 sccm to about 3,000sccm, about 2,000 sccm to about 4,000 sccm, about 2,000 sccm to about5,000 sccm, about 3,000 sccm to about 4,000 sccm, about 3,000 sccm toabout 5,000 sccm, or about 4,000 sccm to about 5,000 sccm. In someembodiments, the gas flow rate is about 50 sccm, about 100 sccm, about250 sccm, about 500 sccm, about 1,000 sccm, about 2,000 sccm, about3,000 sccm, about 4,000 sccm, or about 5,000 sccm.

In some embodiments, the cartridge 500 is connected to the plasmamanifold 200 of the print head through a dielectric spacer 507. In somecases, the dielectric spacer 507 is placed inside the coupler assembly508. A purpose of the dielectric spacer 507 is to carry the aerosol intothe plasma manifold 200. Another purpose is to prevent electrical arcingbetween an electrode 221 in the plasma manifold and the atomizer 501both of which comprise a metal capable of conducting electrons.

In some embodiments, a high voltage can be applied to at least twoelectrodes 221 and 231 to generate plasma. If there is a directlyexposed metallic surface closer to any electrode such as electrode 221,this can result in electrical arcing and/or suppress the plasmagenerated between the electrodes 221 and 231. In order to prevent arcingbetween metal-containing atomizer 501 and electrode 221, they both needto be separated by a dielectric spacer 507. The dielectric spacer lengthshould be larger than the distance between the electrodes, such as thedistance between electrode 221 and electrode 231 in the plasma manifold200. An objective of the spacer 507 is to prevent electrical arcingbetween the top electrode 221 of the plasma manifold and any metallicportion of the cartridge such at the metal-containing atomizer 501. Insome cases, the dielectric spacer 507 may have a smooth inner surface toprevent adsorption of aerosolized ink onto the inner surface resultingin any loss of aerosolized ink to the walls of the spacer.

In some embodiments, the distance between the first electrode and thesecond electrode is about 5 mm to about 40 mm. In some embodiments, thedistance between the first electrode and the second electrode is atleast about 5 mm. In some embodiments, the distance between the firstelectrode and the second electrode is at most about 40 mm. In someembodiments, the distance between the first electrode and the secondelectrode is about 5 mm to about 10 mm, about 5 mm to about 15 mm, about5 mm to about 20 mm, about 5 mm to about 25 mm, about 5 mm to about 30mm, about 5 mm to about 35 mm, about 5 mm to about 40 mm, about 10 mm toabout 15 mm, about 10 mm to about 20 mm, about 10 mm to about 25 mm,about 10 mm to about 30 mm, about 10 mm to about 35 mm, about 10 mm toabout 40 mm, about 15 mm to about 20 mm, about 15 mm to about 25 mm,about 15 mm to about 30 mm, about 15 mm to about 35 mm, about 15 mm toabout 40 mm, about 20 mm to about 25 mm, about 20 mm to about 30 mm,about 20 mm to about 35 mm, about 20 mm to about 40 mm, about 25 mm toabout 30 mm, about 25 mm to about 35 mm, about 25 mm to about 40 mm,about 30 mm to about 35 mm, about 30 mm to about 40 mm, or about 35 mmto about 40 mm. In some embodiments, the distance between the firstelectrode and the second electrode is about 5 mm, about 10 mm, about 15mm, about 20 mm, about 25 mm, about 30 mm, about 35 mm, or about 40 mm.

In some embodiments, the distance between the electrodes is about 1 mmto about 180 mm. In some embodiments, the distance between theelectrodes is at least about 1 mm. In some embodiments, the distancebetween the electrodes is at most about 180 mm. In some embodiments, thedistance between the electrodes is about 1 mm to about 10 mm, about 1 mmto about 25 mm, about 1 mm to about 50 mm, about 1 mm to about 75 mm,about 1 mm to about 100 mm, about 1 mm to about 125 mm, about 1 mm toabout 150 mm, about 1 mm to about 180 mm, about 10 mm to about 25 mm,about 10 mm to about 50 mm, about 10 mm to about 75 mm, about 10 mm toabout 100 mm, about 10 mm to about 125 mm, about 10 mm to about 150 mm,about 10 mm to about 180 mm, about 25 mm to about 50 mm, about 25 mm toabout 75 mm, about 25 mm to about 100 mm, about 25 mm to about 125 mm,about 25 mm to about 150 mm, about 25 mm to about 180 mm, about 50 mm toabout 75 mm, about 50 mm to about 100 mm, about 50 mm to about 125 mm,about 50 mm to about 150 mm, about 50 mm to about 180 mm, about 75 mm toabout 100 mm, about 75 mm to about 125 mm, about 75 mm to about 150 mm,about 75 mm to about 180 mm, about 100 mm to about 125 mm, about 100 mmto about 150 mm, about 100 mm to about 180 mm, about 125 mm to about 150mm, about 125 mm to about 180 mm, or about 150 mm to about 180 mm. Insome embodiments, the distance between the electrodes is about 1 mm,about 10 mm, about 25 mm, about 50 mm, about 75 mm, about 100 mm, about125 mm, about 150 mm, or about 180 mm.

In some embodiments, the electrodes 221 and 231 are connected to anexternal high voltage power supply. In some cases, the electrodes 221and 231 can be dispersed on the outer surface of the primary dielectrictube 210. Plasma is generated in the primary dielectric tube 210 uponintroduction of gas and high voltage potential. The gas inlet 505 can beone, or more than one (not shown), to allow for tuning of one or morematerial properties. For example, hydrogen can be introduced in additionto helium or argon to reduce copper oxide while printing copper and forexample, oxygen can be introduced in addition to helium or argon topolymerize the hexamethyldisiloxane or tetraethyl orthosilicate, forprinting silicon dioxide.

FIG. 28 provides an exemplary fluid delivery assembly 510 comprising acartridge 500. In this exemplary embodiment, the cartridge 500 comprisesan atomizer 501, an ink reservoir 502, at least two of a liquid inletand/or outlet, such as inlet and/or outlet 503 and 504, a gas inlet 505,a lip 506, and a spacer 507.

In this exemplary embodiment, the fluid delivery module can be detachedinto two separate portions: (a) coupler assembly 508 comprising adielectric spacer 507, and gas inlet 505; and (b) a cartridge 500comprising an ink reservoir 502, an atomizer 501, one or more fluidinlet and/or outlet 503 and 504, and a lip 506.

FIG. 29 provides an exemplary multi-material fluid delivery system withtwo cartridges 600 a and 600 b. Both cartridges can be mounted in afluid delivery assembly 610. Each cartridge 600 a and 600 b comprises anink reservoir, 602 a and 602 b, respectively, and also comprises anatomizer 601 a and 601 b, respectively.

A gas inlet 605 a can be a single inlet. In some cases, another gasinlet (not shown) can also be introduced. Each cartridge comprises afluid inlet 603 a and 603 b, respectively; and comprises a fluid outlet604 a and 604 b, respectively.

In some cases, each cartridge comprises a lip 606 a and 606 b. In somecases, both cartridges can either be mounted to a single coupler 608with a single dielectric spacer 607. In some cases, the second cartridge600 b can be mounted on the primary cartridge 600 a.

The entire multi material fluid delivery assembly 610 can be connectedto plasma manifold 200 of the plasma jet print head in a leak tightmanner.

FIG. 30 shows a fluid delivery assembly with a cartridge mountedvertically on a coupler. The fluid delivery assembly 710 comprises acartridge 700. In this exemplary embodiment, the cartridge 700 comprisesan atomizer 701, an ink reservoir 702, at least two liquid inlets and/oroutlets 703 and 704, a gas inlet 705, a lip 706, and a dielectric spacer707. In some cases, the fluid delivery module can be detached into twoseparate portions: (a) a coupler assembly 708 comprising a dielectricspacer 707 and a gas inlet 705; and (b) a cartridge 700 comprising inkreservoir 702, an atomizer 701, a fluid inlet/outlet 703 and 704, and alip 706.

Provided herein is a fluid delivery system for aerosol assisted plasmajet printing of a variety of materials such as copper, silver, gold,titanium dioxide, silicon dioxide, or a combination thereof. In somecases, the material may have one or more organic functionalitiesincluding amine functionalization and carboy functionalization. In somecases, the material comprises a composite such as copper-titaniumdioxide. In some cases, the material comprises a hybrid coating likesilicon dioxide with gold nanoparticles. The fluid delivery system is amodular system comprising with a cartridge and dielectric spacer thatcan be assembled and/or dissembled from a plasm jet print head.

In some embodiments, the fluid delivery system comprises an atomizer. Insome cases, the atomizer comprises an electrically controllable aerosolgenerator. In some cases, the atomizer comprises a perforated plate aplurality of holes.

Several properties of the atomizer can be controlled with high precisionto achieve printing results of interest. In some cases, the propertiescan include the size of the holes of the perforated plate, the vibrationfrequency, the amplitude, the surface energy, or a combination thereof.In some cases, the atomizer can be attached and detached as needed fromthe plasma print head assembly.

In some embodiments, the fluid delivery system comprises an inkreservoir for storing and delivering ink to the atomizer. After the inkis aerosolized in the atomizer, the aerosolized ink is delivered to aprint head.

In some embodiments, the fluid delivery system comprises an atomizersituated at a bottom surface of an ink reservoir.

In some embodiments, the fluid delivery system comprises a gas inlet ata bottom side of an atomizer. In some cases, the gas inlet is locatedbelow the atomizer to carry the aerosol from the atomizer into a printhead. Within the print head, the aerosol can be used to generate plasma.

In some embodiments, the fluid delivery system comprises a lip. In somecases, the lip is situated at a bottom section of the atomizer assembly.A purpose of the lip is to prevent any aerosol generated from theatomizer from being directly exposed to high pressure gas with a highflow rate from the gas inlet.

In some embodiments, the fluid delivery system comprises a dielectricspacer. In some cases, the dielectric spacer comprises a non-conductivematerial with smooth inner surface. The dielectric spacer can connectthe atomizer assembly to the plasma jet print head.

In some cases, the length of the dielectric spacer is larger than thedistance between the at least two electrodes in the plasma jet printhead. This prevents arcing between the top electrode of the print headand the metallic atomizer placed in the assembly. In some embodiments,the length of the dielectric spacer cannot be equal to or less than thedistance between the two electrodes to avoid arcing between the atomizerand the top electrode.

In some embodiments, the fluid delivery system comprises an inkreservoir. In some cases, the ink reservoir provides a continuous supplyof ink to the atomizer and the print head from a large ink storage tankthrough a liquid inlet and a liquid outlet. The liquid inlet and theliquid outlet may be connected to the top of the ink reservoir.

In some cases, the ink reservoir is large enough to provide pre-loadedink to the atomizer. In this configuration, the fluid delivery assemblycomprises a self-contained enclosed cartridge with pre-loaded ink.

In some embodiments, two or more atomizers can be attached to adielectric spacer of the fluid delivery assembly. In some embodiments,two or more ink reservoir units can be attached to a dielectric space ofthe fluid delivery assembly. In those cases, the first atomizer and/orink reservoir can be attached to the side of the dielectric spacer; andthe second atomizer and/or ink reservoir can be attached to the top ofthe dielectric spacer.

A fluid delivery assembly comprising two or more atomizers and two ormore ink reservoirs can be used to introduce two or more aerosols intothe plasma jet print head for printing. In some cases, the two or moreaerosols comprise the same material. In other cases, the two or moreaerosols comprise different materials. A fluid delivery assemblycomprising two or more atomizers and two or more ink reservoirs can beused for printing two or more materials in hybrid coatings, composites,polymers, alloys, or a combination using a single print head. In othercases, a fluid delivery assembly comprising two or more atomizers andtwo or more ink reservoirs can be used for multi-layered printing usinga single print head. In some embodiments, the fluid delivery assemblycomprises an atomizer, a spacer and a print head all connected in aleak-time manner such that no arcing occurs.

Example

In an exemplary embodiment, copper can be printed on low glasstransition temperature plastics such as polyethylene terephthalate andpolycarbonate. The print head that can be used in this exemplaryembodiment comprises a fluid delivery assembly and a plasma manifold.

The fluid delivery assembly comprises a cartridge. In this exemplaryembodiment, the cartridge comprises an atomizer, an ink reservoir with avolume of about 2544 mm³; a liquid inlet; a liquid outlet; a gas inlet;a lip with a length of about 4 mm;, and a spacer. a dielectric spacer507 with a length of about 70 mm, an inner diameter of about 10 mm andan outer diameter of about 13 mm; and a lip 506 with a length of about 4mm.

To print, a gas is introduced into the fluid delivery assembly throughthe gas inlet at a gas flow rate of about 600 sccm.

The operating frequency of the atomizer is about 116 KHz and theatomization rate set at about 40% of the maximum allowed atomization atthis frequency. The atomization rate can be increased by increasing thevoltage input to the atomizer. At atomization rates above 60%, moreaerosol enters the plasma region and the printed pattern is wet andnon-uniform as opposed to dry and uniform pattern at a lower atomizationrate. In addition, when the atomization rate is higher, more aerosolenters the plasma region and prevents uniform plasma generation betweenthe electrodes. An optimal atomization rate is 40 to 50% of theatomization rate. The externally applied high voltage is in the range ofabout 2 kV to about 6 kV and the frequency is in the range of about 30KHz to about 60 KHz.

The plasma manifold comprises a primary dielectric tube. The dielectrictube has an outer diameter of about 6 mm and an inner diameter of about4 mm. The plasma manifold further comprises at least two electrodes. Theseparation between the two electrodes is about 30 mm.

Argon gas flowing at a rate of about 600 sccm can be used to generateplasma in the plasma manifold. The plasma can tune the oxidation stateof copper oxide to copper. In soem cases, hydrogen gas can be added tothe argon gas, by flowing hydrogen gas at a gas flow rate of about 50sccm. In some cases, the combination of hydrogen and gas can occurduring printing. In some cases, the combination can occur after plasmatreatment to tune the oxidation state of copper oxide to copper.

The substrate that is being printed on can be about 3 mm to about 5 mmThe working distance between the printer orifice and the substrate canbe varied from about 3 mm to about 5 mm. At working distance lower than3 mm, the substrate may get affected by the temperature in the plasmaprint head and may result in partial melting of the substrate. At largerworking distance above 7 mm, the plasma effect is very minimal and theadhesion of the printed pattern could be poor.

The conditions are important to attain the desired printingcharacteristics. For example, when the applied voltage is below 2 kV,the plasma intensity and temperature are minimal and the coppernanomaterial passing through the plasma region does not undergosignificant morphological change. For example, when the electrodeseparation is minimal at about 10 mm, and when the applied potential islow, the impact of plasma species on the copper nanomaterials is veryminimal and does not cause morphological and/or oxidation change. Theparticles retain the particle size and shape; this does not result in auniform and conducting film.

When higher potential is used in combination with larger electrodeseparation of 10 mm or more and in the presence of hydrogen, the copperoxide in the aerosol is reduced in-situ printing and a conductingmetallic copper pattern is formed on the substrate. In some cases,post-treatment using argon and hydrogen gas mixture ensures a uniformand conducting film.

In some cases, it may be difficult to print copper on some substratessuch as glass, quartz, ceramics, due to poor adhesion at the lowtemperatures during deposition. Such substrates can withstand hightemperatures however. In such cases, the distance between the electrodescan be greater than about 30 mm to ensure a hot and intense plasmabetween the electrodes, and to increase the residence time of the coppernanomaterial in the plasma region. In some cases, the externally appliedpotential can be above 6 kV and/or the working distance between thesubstrate and the print head can be from about 2 mm to about 5 mm. Theatomization rate can be from about 40 to about 50% of the maximumatomization rate, to avoid more copper nanoparticles being aerosolizedand entered through the plasma that could potentially prevent uniformplasma discharge. This will also result in a wet film deposition and themorphology and oxidation state of copper oxide might remain the same.Printing conditions such as larger electrode separation, higherpotential, lower working distance, higher hydrogen content in the gasmixture, and longer post-treatment time will result in a film withbetter adhesion to glass, quartz, other ceramic materials,polytetrafluoroethylene (PTFE) type of substrates and increasedconductivity closer to that of the bulk copper.

For printing copper on substrates like glass, quartz, ceramic etc., thatcan withstand higher temperature and where the adhesion of printedcopper becomes an issue when deposited at lower temperature, thedistance between the electrodes is increased to over 30 mm to ensure ahotter and intense plasma between the electrodes and to increase theresidence time of the copper nano materials in the plasma region. Alsothe externally applied potential can be increased further above 6 kilovolts and the working distance between the substrate and print head canbe minimized to stay between 2 mm to 5 mm. The atomization rate shouldremain optimal at 40 to 50% of the maximum atomization rate, to avoidmore copper nanoparticles being aerosolized and entered through theplasma that could potentially prevent uniform plasma discharge. Also,this will result in a wet film deposition and the morphology andoxidation state of copper oxide might remain the same. Larger electrodeseparation, higher potential, lower working distance, higher hydrogencontent in the gas mixture, longer post treatment tie etc., will resultin a film with better adhesion to glass, quartz, other ceramicmaterials, polytetrafluoroethylene (PTFE) type of substrates and alsoincreased conductivity closer to that of the bulk copper.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

1.-24. (canceled)
 25. A method for multi-material plasma jet printing,comprising: (a) providing a plasma module, a cartridge, and a dielectricspacer disposed between the plasma module and the cartridge, wherein theplasma module comprises a dielectric tube, a first electrode, and asecond electrode, wherein the dielectric spacer has a length that isgreater than a distance between respective centers of the firstelectrode and the second electrode, and wherein the cartridge comprisesan atomizer; (b) aerosolizing an ink, using the atomizer, to generate anaerosolized ink; (c) flowing the aerosolized ink, through the dielectricspacer, from the cartridge to the plasma module; (d) exposing theaerosolized ink to plasma generated by the first and second electrode ofthe plasma module to generate a plasma-treated aerosolized ink; and (e)printing the plasma-treated aerosolized ink on a substrate.
 26. Themethod of claim 25, further comprising, sequentially after (b)-(e), (f)aerosolizing a second ink, using a second atomizer of a secondcartridge, to generate a second aerosolized ink; (g) flowing the secondaerosolized ink, through the dielectric spacer, from the secondcartridge to the plasma module; (h) exposing the second aerosolized inkto plasma generated by the first and second electrode of the plasmamodule to generate a second plasma-treated aerosolized ink; and (i)printing the second plasma-treated aerosolized ink.
 27. The method ofclaim 25, further comprising, simultaneously with (b)-(e), (f)aerosolizing a second ink, using a second atomizer of a secondcartridge, to generate a second aerosolized ink; (g) flowing the secondaerosolized ink, through the dielectric spacer, from the secondcartridge to the plasma module; (h) exposing the second aerosolized inkto plasma generated by the first and second electrode of the plasmamodule to generate a second plasma-treated aerosolized ink; and (i)printing the second plasma-treated aerosolized ink.
 28. The method ofclaim 25, wherein the first electrode and the second electrode areencapsulated with one or more dielectric materials to prevent arcingbetween the first electrode and the second electrode.
 29. The method ofclaim 28, wherein the first electrode is encapsulated with a firstdielectric material and the second electrode is encapsulated with asecond dielectric material to prevent arcing between the first electrodeand the second electrode.
 30. The method of claim 28, wherein the one ormore dielectric materials has a thickness that is greater than athickness of the dielectric tube.
 31. The method of claim 30, whereinthe one or more dielectric materials has a thickness that is at leastthree times greater than a thickness of the dielectric tube.
 32. Themethod of claim 25, wherein the first electrode and the second electrodeare located on the outside of the dielectric tube.
 33. The method ofclaim 25, wherein the first electrode is located on the outside of thedielectric tube, and the second electrode is located on the inside ofthe dielectric tube.
 34. The method of claim 25, wherein the firstelectrode has a first surface area different from a second surface areaof the second electrode.
 35. The method of claim 25, wherein a distancebetween the first electrode and the second electrode is adjustable. 36.The method of claim 25, wherein both of the first electrode and thesecond electrode are configured to move in the direction along thelength of the dielectric tube.
 37. The method of claim 25, furthercomprising introducing a gas into the cartridge, and wherein the firstelectrode and the second electrode are configured to generate the plasmawithin the dielectric tube in presence of the gas.
 38. The method ofclaim 25, wherein the atomizer comprises a piezo electric atomizer. 39.The method of claim 38, wherein the piezo electric atomizer operates ata frequency of from about 50 kHz to about 10 MHz.
 40. The method ofclaim 25, further comprising attaching or detaching a detachable nozzlemodule to a proximal end of the plasma module, wherein theplasma-treated aerosolized ink is printed on the substrate via a nozzleof the detachable nozzle module.
 41. The method of claim 25, wherein (a)comprises providing two or more cartridges in fluid communication withthe plasma module.
 42. The method of claim 25, wherein the cartridgecomprises an ink inlet that allows entry of the ink into the cartridge.43. The method of claim 25, wherein the exposing in (h) of theaerosolized ink alters a property of the aerosolized ink.